iOS Swift Hw用于访问在完成处理程序闭包中创建的数据 - 在闭包
我有一些使用
创建MapKit方向的代码directions.calculateDirectionsWithCompletionHandler({(response, error) in
方法
代码工作正常 - 在完成处理程序中，但我无法弄清楚如何访问完成处理程序之外的数据。我已经定义了在完成处理程序之外使用的变量。
我意识到完成处理程序是异步运行的，但我不知道如何做以弥补这一点。
最后，提供的代码位于Swift Playground中，因为完成处理程序闭包在那里运行 - 在应用程序中，由于SSL错误，完成处理程序闭包永远不会运行。
这里的代码尽可能少：
//: Playground - noun: a place where people can play
import UIKit
import MapKit
import CoreLocation
import Contacts
import XCPlayground
XCPSetExecutionShouldContinueIndefinitely()
var directionsArray = [String]()
var addressString = ""
// Identify the Source and Destination
let source = MKMapItem(placemark: MKPlacemark(
coordinate: CLLocationCoordinate2DMake(32.2345760,-110.8444420), addressDictionary: nil))
let destination = MKMapItem(placemark: MKPlacemark(
coordinate: CLLocationCoordinate2DMake(34.104908,-118.137903), addressDictionary: nil))
let theLocation = CLLocation(latitude: source.placemark.coordinate.latitude, longitude: source.placemark.coordinate.longitude)
let directionsRequest = MKDirectionsRequest()
directionsRequest.source = source
directionsRequest.destination = destination
directionsRequest.requestsAlternateRoutes = true
let directions = MKDirections(request: directionsRequest)
print("before: directions.calculateDirectionsWithCompletionHandler addressString: \(addressString)")
print("before: directions.calculateDirectionsWithCompletionHandler directionsArray: \(directionsArray)")
directions.calculateDirectionsWithCompletionHandler({(response, error) in
var selectedRoute = 1
addressString += "\n source: 6922 E 1st St, 85710 Tucson, AZ United States"
addressString += "\n Destination: 2014–2048 Huntington Dr, 91030 South Pasadena, CA United States"
print("\nwithin: directions.calculateDirectionsWithCompletionHandler: \n")
print("error: \(error)")
print("response!.routes.count \(response!.routes.count)")
print("response!.routes[selectedRoute] \(response!.routes[selectedRoute])")
let theSteps = response?.routes[selectedRoute].steps.count as Int!
print("theSteps: \(theSteps)")
print("distance: \(response!.routes[selectedRoute].distance) meters") // time \(response?.routes.first?.time)")
addressString += "\n distance: \(response!.routes[selectedRoute].distance) meters"
let myRoute = response?.routes[selectedRoute]
print("myRoute!.polyline.pointCount \(myRoute!.polyline.pointCount)")
print("myRoute!.steps[0].polyline.points(): \(myRoute!.steps[0].polyline.points())")
print("polyline.points \(myRoute!.polyline.points())")
// Build an array of Route Step Coordinates for later inclusion in Directions
var stepCoordinates = [CLLocationCoordinate2D]()
for step in myRoute!.steps as [MKRouteStep] {
let pointCount = step.polyline.pointCount
var cArray = UnsafeMutablePointer<CLLocationCoordinate2D>.alloc(pointCount)
step.polyline.getCoordinates(cArray, range: NSMakeRange(0, pointCount))
for var c=0; c < pointCount; c++ {
let coord = cArray[c]
if c == 0 {
var theCoordinate = CLLocationCoordinate2DMake(coord.latitude, coord.longitude)
stepCoordinates.append(theCoordinate)
}
}
cArray.dealloc(pointCount)
}
// get the Directions Steps including the latitidude / longitude from thearray of Step Coordinates
for index in 0..<theSteps {
let lat = stepCoordinates[index].latitude
let lon = stepCoordinates[index].longitude
directionsArray.append("\n steps[\(index)] \(lat),\(lon) - \(myRoute!.steps[index].distance) meters - \(myRoute!.steps[index].instructions)")
}
print("\nwithin: directions.calculateDirectionsWithCompletionHandler: addressString: \(addressString)")
print("\nwithin: directions.calculateDirectionsWithCompletionHandler: directionsArray: \(directionsArray)")
})
print("\nafter: directions.calculateDirectionsWithCompletionHandler: addressString: \(addressString)")
print("after: directions.calculateDirectionsWithCompletionHandler: directionsArray: \(directionsArray)\n")
这是控制台输出：
之前：directions.calculateDirectionsWithCompletionHandler addressString：
before: directions.calculateDirectionsWithCompletionHandler directionsArray: []
after: directions.calculateDirectionsWithCompletionHandler: addressString:
after: directions.calculateDirectionsWithCompletionHandler: directionsArray: []
2015-07-06 14:00:58.421 GetDirectionsBasic[9758:4735303] Failed to obtain sandbox extension for path=/var/folders/7l/cgpb6wr9489b1qhxl8y38hvm0000gn/T/com.apple.dt.Xcode.pg/containers/com.apple.dt.playground.stub.iOS_Simulator.GetDirectionsBasic-98692A18-CEBC-4354-8E6A-5B12BA647B9E/Library/Caches/com.apple.dt.playground.stub.iOS_Simulator.GetDirectionsBasic-98692A18-CEBC-4354-8E6A-5B12BA647B9E. Errno:1
2015-07-06 14:00:58.422 GetDirectionsBasic[9758:4735303] Failed to obtain sandbox extension for path=/var/folders/7l/cgpb6wr9489b1qhxl8y38hvm0000gn/T/com.apple.dt.Xcode.pg/containers/com.apple.dt.playground.stub.iOS_Simulator.GetDirectionsBasic-98692A18-CEBC-4354-8E6A-5B12BA647B9E/Library/Caches/com.apple.dt.playground.stub.iOS_Simulator.GetDirectionsBasic-98692A18-CEBC-4354-8E6A-5B12BA647B9E. Errno:1
within: directions.calculateDirectionsWithCompletionHandler:
error: nil
response!.routes.count 3
response!.routes[selectedRoute] <MKRoute: 0x7fd7e0549220>
theSteps: 15
distance: 821009.0 meters
myRoute!.polyline.pointCount 2743
myRoute!.steps[0].polyline.points(): 0x00007fd7e1073000
polyline.points 0x00007fd7e1073000
within: directions.calculateDirectionsWithCompletionHandler: addressString:
source: 6922 E 1st St, 85710 Tucson, AZ United States
Destination: 2014–2048 Huntington Dr, 91030 South Pasadena, CA United States
distance: 821009.0 meters
within: directions.calculateDirectionsWithCompletionHandler: directionsArray: [
steps[0] 32.2345979232341,-110.844443056463 - 0.0 meters - Proceed to E 1st St,
steps[1] 32.2345979232341,-110.844443056463 - 105.0 meters - At the end of the road, turn left onto N Green Hills Ave,
steps[2] 32.2345979232341,-110.843325078218 - 117.0 meters - Turn left onto E Speedway Blvd,
steps[3] 32.2356559708714,-110.843304039641 - 13216.0 meters - Turn right onto N Freeway Rd toward Phoenix,
steps[4] 32.235831990838,-110.983517018841 - 132.0 meters - Keep left to merge onto I-10 W,
steps[5] 32.236999925226,-110.9837630277 - 92506.0 meters - Take exit 199 to merge onto I-8 W toward San Diego,
steps[6] 32.8114569280297,-111.674388011842 - 374340.0 meters - Take exit 118B onto CA-111 N toward Indio,
steps[7] 32.773857973516,-115.495294079998 - 33287.0 meters - Turn right onto State Highway 86,
steps[8] 33.0002589616925,-115.585204073131 - 107741.0 meters - Continue onto I-10 W,
steps[9] 33.7204659450799,-116.19523705826 - 184120.0 meters - Keep left,
steps[10] 34.0650959406048,-118.013762030288 - 11125.0 meters - Take exit 23A onto Atlantic Blvd,
steps[11] 34.0716939233243,-118.132452042339 - 103.0 meters - Keep right on S Atlantic Blvd,
steps[12] 34.0717909857631,-118.133564069433 - 3815.0 meters - Turn left onto Garfield Ave,
steps[13] 34.1057089436799,-118.134696045456 - 108.0 meters - Turn left onto Huntington Dr,
steps[14] 34.1065149474889,-118.13535704234 - 294.0 meters - The destination is on your left]
3 个答案:
答案 0 :(得分：3)
你是对的，这里有一个关于异步性的根本问题。它实际上与MapKit或代码的大部分其他细节无关，所以我在后面的答案中抽象了它们。
＆＃34;异步＆＃34;意味着，对于任何看起来像这样的东西：
...绿色和蓝色块在 棕色块之前运行 ：
（另外，蓝色和棕色块之间的时间可以任意短或长，主线程在此期间更新UI。）
这意味着：
-
蓝色块中的任何代码都不知道棕色块中发生的事情，因为它还没有发生。 （如果发生其他情况，你违反了因果关系......通知斯蒂芬霍金。并提交雷达。）
-
由于棕色块中的代码需要从棕色块内触发，您想要发生的任何事情。 （或者来自其他地方，保证是＆＃34;之后＆＃34;。）
这也意味着，如果您正在尝试使用以下模式：
func getDirections() -> String {
var directions: [String]
getMKDirectionsWithCompletionHandler() { result, error in
directions = // something from result
}
return directions
}
......你的设计根本不可行。您需要查看要调用getDirections()函数的位置并使用其结果，并将它们设计为异步。
例如，如果你想做这样的事情：
let theDirections = getDirections()
destinationLabel.text = theDirections.last!
你需要做这样的事情：
getMKDirectionsWithCompletionHandler() { result, error in
let directions: [String] = // something from result
destinationLabel.text = directions.last! // use it *in* the completion block
}
或者，请记住我的说法＆＃34;其他地方保证会更晚些时候＆＃34;？假设您要在表视图中显示这些字符串：
class MyViewController: UITableViewController {
var directions = [String]()
func viewWillAppear() {
getMKDirectionsWithCompletionHandler() { result, error in
directions = // something from result
// make sure the UI updates after we have our result
self.tableView.reloadData()
}
}
func tableView(tv: UITableView, numberOfRowsInSection section: Int) -> Int {
return directions.count
}
func tableView(tv: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
let directionsItem = directions[indexPath.row]
return // cell constructed from directionsItem
}
}
答案 1 :(得分：1)
借助@matt的延迟例程和来自@ gooroo7的文件读/写例程，这是Playground中的一个工作示例......
由于启动获取路线请求时出现SSL握手问题，我无法让它在应用内运行：
mapDirections.calculateDirectionsWithCompletionHandler({(response, error) in
我已经包含了相当冗长的代码和控制台输出。来自@matt和@ gooroo7的例程记录在哪里使用。此外，控制台输出相当长 - 显示文件和使用的变量的之前，期间和之后（关闭）状态。
这是Playground代码：
//: Playground - noun: a place where people can play
import UIKit
import MapKit
import CoreLocation
import Contacts
import XCPlayground
XCPSetExecutionShouldContinueIndefinitely()
var directionsArray = [String]()
var addressString = String()
func setAddressString(theString:String){
addressString = theString
print("setAddressString \(addressString)")
}
// http://stackoverflow.com/questions/24097826/read-and-write-data-from-text-file
// answer by goroo7
//To avoid confusion and add ease, I have created two functions for reading and writing strings to files in the documents directory. Here are the functions:
//--------------------------------------------------------------------------------------------------------------
func writeToDocumentsFile(fileName:String,value:String) {
let documentsPath = NSSearchPathForDirectoriesInDomains(.DocumentDirectory, .UserDomainMask, true)[0] // as! NSString
let path = documentsPath.stringByAppendingPathComponent(fileName)
// var error:NSError?
do {
try value.writeToFile(path, atomically: true, encoding: NSUTF8StringEncoding) //, error: nil)
}
catch let error as NSError {
// Catch fires here, with an NSErrror being thrown from the value.writeToFile method
print("A write to file error occurred, here are the details:\n \(error)")
}
}
func readFromDocumentsFile(fileName:String) -> String {
let documentsPath = NSSearchPathForDirectoriesInDomains(.DocumentDirectory, .UserDomainMask, true)[0] //as! NSString
let path = documentsPath.stringByAppendingPathComponent(fileName)
let checkValidation = NSFileManager.defaultManager()
// var error:NSError?
// var file:String
var file = ""
if checkValidation.fileExistsAtPath(path) {
do {
try file = NSString(contentsOfFile: path, encoding: NSUTF8StringEncoding) as String
}
catch let error as NSError {
// Catch fires here, with an NSErrror being thrown from the JSONObjectWithData method
print("A read from file error occurred, here are the details:\n \(error)")
}
} else {
file = "*ERROR* \(fileName) does not exist."
}
print("return file: \(file)")
return file
}
//--------------------------------------------------------------------------------------------------------------
func getDirections() {
print("getDirections")
// Identify the Source and Destination
let source = MKMapItem(placemark: MKPlacemark(
coordinate: CLLocationCoordinate2DMake(32.2345760,-110.8444420), addressDictionary: nil))
let destination = MKMapItem(placemark: MKPlacemark(
coordinate: CLLocationCoordinate2DMake(34.104908,-118.137903), addressDictionary: nil))
let theLocation = CLLocation(latitude: source.placemark.coordinate.latitude, longitude: source.placemark.coordinate.longitude)
let directionsRequest = MKDirectionsRequest()
directionsRequest.source = source
directionsRequest.destination = destination
directionsRequest.requestsAlternateRoutes = true
let mapDirections = MKDirections(request: directionsRequest)
print("before: directions.calculateDirectionsWithCompletionHandler addressString: \(addressString)")
print("before: directions.calculateDirectionsWithCompletionHandler directionsArray: \(directionsArray)\n")
mapDirections.calculateDirectionsWithCompletionHandler({(response, error) in
let selectedRoute = 1
let todaysDate:NSDate = NSDate()
let dateFormatter:NSDateFormatter = NSDateFormatter()
dateFormatter.dateFormat = "MM-dd-yyyy HH:mm"
let DateInFormat:String = dateFormatter.stringFromDate(todaysDate)
//print("\nDateInFormat: \(DateInFormat)\n")
addressString = "\n..........addressString" //\n \(DateInFormat)"
addressString += ("\n Date \(DateInFormat)")
addressString += ("\n source: 6922 E 1st St, 85710 Tucson, AZ United States")
addressString += ("\n Destination: 2014–2048 Huntington Dr, 91030 South Pasadena, CA United States")
print("\nwithin: directions.calculateDirectionsWithCompletionHandler: \n")
print("error: \(error)")
print("response!.routes.count \(response!.routes.count)")
print("response!.routes[selectedRoute] \(response!.routes[selectedRoute])")
let theSteps = response?.routes[selectedRoute].steps.count as Int!
print("theSteps: \(theSteps)")
print("distance: \(response!.routes[selectedRoute].distance) meters") // time \(response?.routes.first?.time)")
addressString += ("\n distance: \(response!.routes[selectedRoute].distance) meters")
let myRoute = response?.routes[selectedRoute]
print("myRoute!.polyline.pointCount \(myRoute!.polyline.pointCount)")
print("myRoute!.steps[0].polyline.points(): \(myRoute!.steps[0].polyline.points())")
print("polyline.points \(myRoute!.polyline.points())")
// Build an array of Route Step Coordinates for later inclusion in Directions
var stepCoordinates = [CLLocationCoordinate2D]()
for step in myRoute!.steps as [MKRouteStep] {
let pointCount = step.polyline.pointCount
var cArray = UnsafeMutablePointer<CLLocationCoordinate2D>.alloc(pointCount)
step.polyline.getCoordinates(cArray, range: NSMakeRange(0, pointCount))
for var c=0; c < pointCount; c++ {
let coord = cArray[c]
if c == 0 {
var theCoordinate = CLLocationCoordinate2DMake(coord.latitude, coord.longitude)
stepCoordinates.append(theCoordinate)
}
}
cArray.dealloc(pointCount)
}
// get the Directions Steps including the latitidude / longitude from thearray of Step Coordinates
for index in 0..<theSteps {
let lat = stepCoordinates[index].latitude
let lon = stepCoordinates[index].longitude
directionsArray.append("\n steps[\(index)] \(lat),\(lon) - \(myRoute!.steps[index].distance) meters - \(myRoute!.steps[index].instructions)")
addressString += ("\n steps[\(index)] \(lat),\(lon) - \(myRoute!.steps[index].distance) meters - \(myRoute!.steps[index].instructions)")
}
// let directions: [String] = addressString
setAddressString(addressString)
print("\nwithin: directions.calculateDirectionsWithCompletionHandler: addressString: \(addressString)")
print("\nwithin: directions.calculateDirectionsWithCompletionHandler: directionsArray: \(directionsArray)")
// http://stackoverflow.com/questions/24097826/read-and-write-data-from-text-file
// answer by goroo7
//To avoid confusion and add ease, I have created two functions for reading and writing strings to files in the documents directory. Here are the functions: ... Here is an example of their use:
//--------------------------------------------------------------------------------------------------------------
writeToDocumentsFile("addressString.txt",value: addressString)
//--------------------------------------------------------------------------------------------------------------
})
}
getDirections()
// http://stackoverflow.com/questions/24034544/dispatch-after-gcd-in-swift/24318861#24318861
// answer by @matt
// I use dispatch_after so often that I wrote a top-level utility function to make the syntax simpler:
//--------------------------------------------------------------------------------------------------------------
func delay(delay:Double, closure:()->()) {
dispatch_after(
dispatch_time(
DISPATCH_TIME_NOW,
Int64(delay * Double(NSEC_PER_SEC))
),
dispatch_get_main_queue(), closure)
}
//And now you can talk like this:
delay(3.0) {
// do stuff
let value = readFromDocumentsFile("addressString.txt")
print("\nAfter Delay - readFromDocumentsFile written in closure: \(value)\n") //Would output 'Hello world!'
print("\nAfter Delay - read from external var addressString updated in closure: \(addressString)")
print("\nAfter Delay - read from external var directionsArray updated in closure:\(directionsArray)")
}
//--------------------------------------------------------------------------------------------------------------
这是控制台输出：
getDirections
before: directions.calculateDirectionsWithCompletionHandler addressString:
before: directions.calculateDirectionsWithCompletionHandler directionsArray: []
2015-07-07 16:12:31.116 GetDirectionsBasic[1768:630471] Failed to obtain sandbox extension for path=/var/folders/7l/cgpb6wr9489b1qhxl8y38hvm0000gn/T/com.apple.dt.Xcode.pg/containers/com.apple.dt.playground.stub.iOS_Simulator.GetDirectionsBasic-9B1F8F3C-4BBC-430F-AEFE-469C81A24CBE/Library/Caches/com.apple.dt.playground.stub.iOS_Simulator.GetDirectionsBasic-9B1F8F3C-4BBC-430F-AEFE-469C81A24CBE. Errno:1
2015-07-07 16:12:31.116 GetDirectionsBasic[1768:630471] Failed to obtain sandbox extension for path=/var/folders/7l/cgpb6wr9489b1qhxl8y38hvm0000gn/T/com.apple.dt.Xcode.pg/containers/com.apple.dt.playground.stub.iOS_Simulator.GetDirectionsBasic-9B1F8F3C-4BBC-430F-AEFE-469C81A24CBE/Library/Caches/com.apple.dt.playground.stub.iOS_Simulator.GetDirectionsBasic-9B1F8F3C-4BBC-430F-AEFE-469C81A24CBE. Errno:1
within: directions.calculateDirectionsWithCompletionHandler:
error: nil
response!.routes.count 3
response!.routes[selectedRoute] <MKRoute: 0x7fed8a212e60>
theSteps: 15
distance: 821009.0 meters
myRoute!.polyline.pointCount 2743
myRoute!.steps[0].polyline.points(): 0x00007fed89052a00
polyline.points 0x00007fed89052a00
setAddressString
..........addressString
Date 07-07-2015 16:12
source: 6922 E 1st St, 85710 Tucson, AZ United States
Destination: 2014–2048 Huntington Dr, 91030 South Pasadena, CA United States
distance: 821009.0 meters
steps[0] 32.2345979232341,-110.844443056463 - 0.0 meters - Proceed to E 1st St
steps[1] 32.2345979232341,-110.844443056463 - 105.0 meters - At the end of the road, turn left onto N Green Hills Ave
steps[2] 32.2345979232341,-110.843325078218 - 117.0 meters - Turn left onto E Speedway Blvd
steps[3] 32.2356559708714,-110.843304039641 - 13216.0 meters - Turn right onto N Freeway Rd toward Phoenix
steps[4] 32.235831990838,-110.983517018841 - 132.0 meters - Keep left to merge onto I-10 W
steps[5] 32.236999925226,-110.9837630277 - 92506.0 meters - Take exit 199 to merge onto I-8 W toward San Diego
steps[6] 32.8114569280297,-111.674388011842 - 374340.0 meters - Take exit 118B onto CA-111 N toward Indio
steps[7] 32.773857973516,-115.495294079998 - 33287.0 meters - Turn right onto State Highway 86
steps[8] 33.0002589616925,-115.585204073131 - 107741.0 meters - Continue onto I-10 W
steps[9] 33.7204659450799,-116.19523705826 - 184120.0 meters - Keep left
steps[10] 34.0650959406048,-118.013762030288 - 11125.0 meters - Take exit 23A onto Atlantic Blvd
steps[11] 34.0716939233243,-118.132452042339 - 103.0 meters - Keep right on S Atlantic Blvd
steps[12] 34.0717909857631,-118.133564069433 - 3815.0 meters - Turn left onto Garfield Ave
steps[13] 34.1057089436799,-118.134696045456 - 108.0 meters - Turn left onto Huntington Dr
steps[14] 34.1065149474889,-118.13535704234 - 294.0 meters - The destination is on your left
within: directions.calculateDirectionsWithCompletionHandler: addressString:
..........addressString
Date 07-07-2015 16:12
source: 6922 E 1st St, 85710 Tucson, AZ United States
Destination: 2014–2048 Huntington Dr, 91030 South Pasadena, CA United States
distance: 821009.0 meters
steps[0] 32.2345979232341,-110.844443056463 - 0.0 meters - Proceed to E 1st St
steps[1] 32.2345979232341,-110.844443056463 - 105.0 meters - At the end of the road, turn left onto N Green Hills Ave
steps[2] 32.2345979232341,-110.843325078218 - 117.0 meters - Turn left onto E Speedway Blvd
steps[3] 32.2356559708714,-110.843304039641 - 13216.0 meters - Turn right onto N Freeway Rd toward Phoenix
steps[4] 32.235831990838,-110.983517018841 - 132.0 meters - Keep left to merge onto I-10 W
steps[5] 32.236999925226,-110.9837630277 - 92506.0 meters - Take exit 199 to merge onto I-8 W toward San Diego
steps[6] 32.8114569280297,-111.674388011842 - 374340.0 meters - Take exit 118B onto CA-111 N toward Indio
steps[7] 32.773857973516,-115.495294079998 - 33287.0 meters - Turn right onto State Highway 86
steps[8] 33.0002589616925,-115.585204073131 - 107741.0 meters - Continue onto I-10 W
steps[9] 33.7204659450799,-116.19523705826 - 184120.0 meters - Keep left
steps[10] 34.0650959406048,-118.013762030288 - 11125.0 meters - Take exit 23A onto Atlantic Blvd
steps[11] 34.0716939233243,-118.132452042339 - 103.0 meters - Keep right on S Atlantic Blvd
steps[12] 34.0717909857631,-118.133564069433 - 3815.0 meters - Turn left onto Garfield Ave
steps[13] 34.1057089436799,-118.134696045456 - 108.0 meters - Turn left onto Huntington Dr
steps[14] 34.1065149474889,-118.13535704234 - 294.0 meters - The destination is on your left
within: directions.calculateDirectionsWithCompletionHandler: directionsArray: [
steps[0] 32.2345979232341,-110.844443056463 - 0.0 meters - Proceed to E 1st St,
steps[1] 32.2345979232341,-110.844443056463 - 105.0 meters - At the end of the road, turn left onto N Green Hills Ave,
steps[2] 32.2345979232341,-110.843325078218 - 117.0 meters - Turn left onto E Speedway Blvd,
steps[3] 32.2356559708714,-110.843304039641 - 13216.0 meters - Turn right onto N Freeway Rd toward Phoenix,
steps[4] 32.235831990838,-110.983517018841 - 132.0 meters - Keep left to merge onto I-10 W,
steps[5] 32.236999925226,-110.9837630277 - 92506.0 meters - Take exit 199 to merge onto I-8 W toward San Diego,
steps[6] 32.8114569280297,-111.674388011842 - 374340.0 meters - Take exit 118B onto CA-111 N toward Indio,
steps[7] 32.773857973516,-115.495294079998 - 33287.0 meters - Turn right onto State Highway 86,
steps[8] 33.0002589616925,-115.585204073131 - 107741.0 meters - Continue onto I-10 W,
steps[9] 33.7204659450799,-116.19523705826 - 184120.0 meters - Keep left,
steps[10] 34.0650959406048,-118.013762030288 - 11125.0 meters - Take exit 23A onto Atlantic Blvd,
steps[11] 34.0716939233243,-118.132452042339 - 103.0 meters - Keep right on S Atlantic Blvd,
steps[12] 34.0717909857631,-118.133564069433 - 3815.0 meters - Turn left onto Garfield Ave,
steps[13] 34.1057089436799,-118.134696045456 - 108.0 meters - Turn left onto Huntington Dr,
steps[14] 34.1065149474889,-118.13535704234 - 294.0 meters - The destination is on your left]
return file:
..........addressString
Date 07-07-2015 16:12
source: 6922 E 1st St, 85710 Tucson, AZ United States
Destination: 2014–2048 Huntington Dr, 91030 South Pasadena, CA United States
distance: 821009.0 meters
steps[0] 32.2345979232341,-110.844443056463 - 0.0 meters - Proceed to E 1st St
steps[1] 32.2345979232341,-110.844443056463 - 105.0 meters - At the end of the road, turn left onto N Green Hills Ave
steps[2] 32.2345979232341,-110.843325078218 - 117.0 meters - Turn left onto E Speedway Blvd
steps[3] 32.2356559708714,-110.843304039641 - 13216.0 meters - Turn right onto N Freeway Rd toward Phoenix
steps[4] 32.235831990838,-110.983517018841 - 132.0 meters - Keep left to merge onto I-10 W
steps[5] 32.236999925226,-110.9837630277 - 92506.0 meters - Take exit 199 to merge onto I-8 W toward San Diego
steps[6] 32.8114569280297,-111.674388011842 - 374340.0 meters - Take exit 118B onto CA-111 N toward Indio
steps[7] 32.773857973516,-115.495294079998 - 33287.0 meters - Turn right onto State Highway 86
steps[8] 33.0002589616925,-115.585204073131 - 107741.0 meters - Continue onto I-10 W
steps[9] 33.7204659450799,-116.19523705826 - 184120.0 meters - Keep left
steps[10] 34.0650959406048,-118.013762030288 - 11125.0 meters - Take exit 23A onto Atlantic Blvd
steps[11] 34.0716939233243,-118.132452042339 - 103.0 meters - Keep right on S Atlantic Blvd
steps[12] 34.0717909857631,-118.133564069433 - 3815.0 meters - Turn left onto Garfield Ave
steps[13] 34.1057089436799,-118.134696045456 - 108.0 meters - Turn left onto Huntington Dr
steps[14] 34.1065149474889,-118.13535704234 - 294.0 meters - The destination is on your left
After Delay - readFromDocumentsFile written in closure:
..........addressString
Date 07-07-2015 16:12
source: 6922 E 1st St, 85710 Tucson, AZ United States
Destination: 2014–2048 Huntington Dr, 91030 South Pasadena, CA United States
distance: 821009.0 meters
steps[0] 32.2345979232341,-110.844443056463 - 0.0 meters - Proceed to E 1st St
steps[1] 32.2345979232341,-110.844443056463 - 105.0 meters - At the end of the road, turn left onto N Green Hills Ave
steps[2] 32.2345979232341,-110.843325078218 - 117.0 meters - Turn left onto E Speedway Blvd
steps[3] 32.2356559708714,-110.843304039641 - 13216.0 meters - Turn right onto N Freeway Rd toward Phoenix
steps[4] 32.235831990838,-110.983517018841 - 132.0 meters - Keep left to merge onto I-10 W
steps[5] 32.236999925226,-110.9837630277 - 92506.0 meters - Take exit 199 to merge onto I-8 W toward San Diego
steps[6] 32.8114569280297,-111.674388011842 - 374340.0 meters - Take exit 118B onto CA-111 N toward Indio
steps[7] 32.773857973516,-115.495294079998 - 33287.0 meters - Turn right onto State Highway 86
steps[8] 33.0002589616925,-115.585204073131 - 107741.0 meters - Continue onto I-10 W
steps[9] 33.7204659450799,-116.19523705826 - 184120.0 meters - Keep left
steps[10] 34.0650959406048,-118.013762030288 - 11125.0 meters - Take exit 23A onto Atlantic Blvd
steps[11] 34.0716939233243,-118.132452042339 - 103.0 meters - Keep right on S Atlantic Blvd
steps[12] 34.0717909857631,-118.133564069433 - 3815.0 meters - Turn left onto Garfield Ave
steps[13] 34.1057089436799,-118.134696045456 - 108.0 meters - Turn left onto Huntington Dr
steps[14] 34.1065149474889,-118.13535704234 - 294.0 meters - The destination is on your left
After Delay - read from external var addressString updated in closure:
..........addressString
Date 07-07-2015 16:12
source: 6922 E 1st St, 85710 Tucson, AZ United States
Destination: 2014–2048 Huntington Dr, 91030 South Pasadena, CA United States
distance: 821009.0 meters
steps[0] 32.2345979232341,-110.844443056463 - 0.0 meters - Proceed to E 1st St
steps[1] 32.2345979232341,-110.844443056463 - 105.0 meters - At the end of the road, turn left onto N Green Hills Ave
steps[2] 32.2345979232341,-110.843325078218 - 117.0 meters - Turn left onto E Speedway Blvd
steps[3] 32.2356559708714,-110.843304039641 - 13216.0 meters - Turn right onto N Freeway Rd toward Phoenix
steps[4] 32.235831990838,-110.983517018841 - 132.0 meters - Keep left to merge onto I-10 W
steps[5] 32.236999925226,-110.9837630277 - 92506.0 meters - Take exit 199 to merge onto I-8 W toward San Diego
steps[6] 32.8114569280297,-111.674388011842 - 374340.0 meters - Take exit 118B onto CA-111 N toward Indio
steps[7] 32.773857973516,-115.495294079998 - 33287.0 meters - Turn right onto State Highway 86
steps[8] 33.0002589616925,-115.585204073131 - 107741.0 meters - Continue onto I-10 W
steps[9] 33.7204659450799,-116.19523705826 - 184120.0 meters - Keep left
steps[10] 34.0650959406048,-118.013762030288 - 11125.0 meters - Take exit 23A onto Atlantic Blvd
steps[11] 34.0716939233243,-118.132452042339 - 103.0 meters - Keep right on S Atlantic Blvd
steps[12] 34.0717909857631,-118.133564069433 - 3815.0 meters - Turn left onto Garfield Ave
steps[13] 34.1057089436799,-118.134696045456 - 108.0 meters - Turn left onto Huntington Dr
steps[14] 34.1065149474889,-118.13535704234 - 294.0 meters - The destination is on your left
After Delay - read from external var directionsArray updated in closure:[
steps[0] 32.2345979232341,-110.844443056463 - 0.0 meters - Proceed to E 1st St,
steps[1] 32.2345979232341,-110.844443056463 - 105.0 meters - At the end of the road, turn left onto N Green Hills Ave,
steps[2] 32.2345979232341,-110.843325078218 - 117.0 meters - Turn left onto E Speedway Blvd,
steps[3] 32.2356559708714,-110.843304039641 - 13216.0 meters - Turn right onto N Freeway Rd toward Phoenix,
steps[4] 32.235831990838,-110.983517018841 - 132.0 meters - Keep left to merge onto I-10 W,
steps[5] 32.236999925226,-110.9837630277 - 92506.0 meters - Take exit 199 to merge onto I-8 W toward San Diego,
steps[6] 32.8114569280297,-111.674388011842 - 374340.0 meters - Take exit 118B onto CA-111 N toward Indio,
steps[7] 32.773857973516,-115.495294079998 - 33287.0 meters - Turn right onto State Highway 86,
steps[8] 33.0002589616925,-115.585204073131 - 107741.0 meters - Continue onto I-10 W,
steps[9] 33.7204659450799,-116.19523705826 - 184120.0 meters - Keep left,
steps[10] 34.0650959406048,-118.013762030288 - 11125.0 meters - Take exit 23A onto Atlantic Blvd,
steps[11] 34.0716939233243,-118.132452042339 - 103.0 meters - Keep right on S Atlantic Blvd,
steps[12] 34.0717909857631,-118.133564069433 - 3815.0 meters - Turn left onto Garfield Ave,
steps[13] 34.1057089436799,-118.134696045456 - 108.0 meters - Turn left onto Huntington Dr,
steps[14] 34.1065149474889,-118.13535704234 - 294.0 meters - The destination is on your left]
感谢所有帮助过的人 - 希望这对其他人有用！
答案 2 :(得分：0)
由于完成处理程序在另一个线程上运行，因此dispatch_async到您要在完成处理程序内部使用数据的线程。这样，您将在实际到达后访问数据。
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