我试图创建一个应用程序，将用户带到我的MySQL数据库中存储的街道地址。 JSON是有效的，我相信URL也是。
我相信正在发生的事情是数据丢失并通过可选绑定返回零。或者URL不正确（我确实在Playground中查看是否会返回nil并且URL没有＆t;）
我一直在关注本教程： http://codewithchris.com/iphone-app-connect-to-mysql-database/ 这是我第一次将应用程序连接到数据库。
我相对较新，很快就试图掌握它。
有什么想法吗？任何帮助将不胜感激。提前谢谢。
我的服务器目前位于专用网络上。但我知道它不会影响API
数据下载但后来所有变量都是nil。 DetailViewController中的应用程序中断
的ViewController
import UIKit
class ViewController: UIViewController, UITableViewDataSource, UITableViewDelegate, HomeModelProtocal {
//Properties
var feedItems: NSArray = NSArray()
var selectedLocation : LocationModel = LocationModel()
@IBOutlet weak var listTableView: UITableView!
override func viewDidLoad() {
super.viewDidLoad()
//set delegates and initialize homeModel
self.listTableView.delegate = self
self.listTableView.dataSource = self
let homeModel = HomeModel()
homeModel.delegate = self
homeModel.downloadItems()
}
func itemsDownloaded(items: NSArray) {
feedItems = items
self.listTableView.reloadData()
}
func tableView(tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
// Return the number of feed items
return feedItems.count
}
func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
// Retrieve cell
let cellIdentifier: String = "BasicCell"
let myCell: UITableViewCell = tableView.dequeueReusableCellWithIdentifier(cellIdentifier)!
// Get the location to be shown
let item: LocationModel = feedItems[indexPath.row] as! LocationModel
// Get references to labels of cell
myCell.textLabel!.text = item.address
return myCell
}
}
LocationModel
import Foundation
class LocationModel: NSObject {
//properties
var name: String?
var address: String?
var latitude: String?
var longitude: String?
//empty constructor
override init()
{
}
//construct with @name, @address, @latitude, and @longitude parameters
init(name: String, address: String, latitude: String, longitude: String) {
self.name = name
self.address = address
self.latitude = latitude
self.longitude = longitude
}
//prints object's current state
override var description: String {
return "Name: \(name), Address: \(address), Latitude: \(latitude), Longitude: \(longitude)"
}
}
HomeModel
import Foundation
protocol HomeModelProtocal: class {
func itemsDownloaded(items: NSArray)
}
class HomeModel: NSObject, NSURLSessionDataDelegate {
//properties
weak var delegate: HomeModelProtocal!
var data : NSMutableData = NSMutableData()
let urlPath: String = "http://dev.devmelb.com/service.php" //this will be changed to the path where service.php lives
func downloadItems() {
let url: NSURL = NSURL(string: urlPath)!
var session: NSURLSession!
let configuration = NSURLSessionConfiguration.defaultSessionConfiguration()
session = NSURLSession(configuration: configuration, delegate: self, delegateQueue: nil)
let task = session.dataTaskWithURL(url)
task.resume()
}
func URLSession(session: NSURLSession, dataTask: NSURLSessionDataTask, didReceiveData data: NSData) {
self.data.appendData(data);
}
func URLSession(session: NSURLSession, task: NSURLSessionTask, didCompleteWithError error: NSError?) {
if error != nil {
print("Failed to download data")
}else {
print("Data downloaded")
print(LocationModel())
print(error)
self.parseJSON()
}
}
func parseJSON() {
var jsonResult: NSMutableArray = NSMutableArray()
do{
jsonResult = try NSJSONSerialization.JSONObjectWithData(self.data, o . ptions:NSJSONReadingOptions.AllowFragments) as! NSMutableArray
} catch let error as NSError {
print(error)
}
var jsonElement: NSDictionary = NSDictionary()
let locations: NSMutableArray = NSMutableArray()
for i in 0 ..< jsonResult.count
{
jsonElement = jsonResult[i] as! NSDictionary
let location = LocationModel()
print(location)
//the following insures none of the JsonElement values are nil through optional binding
if let name = jsonElement["Name"] as? String,
let address = jsonElement["Address"] as? String,
let latitude = jsonElement["Latitude"] as? String,
let longitude = jsonElement["Longitude"] as? String
{
location.name = name
location.address = address
location.latitude = latitude
location.longitude = longitude
}
locations.addObject(location)
}
dispatch_async(dispatch_get_main_queue(), { () -> Void in
self.delegate.itemsDownloaded(locations)
})
}
}
DetailViewController
import Foundation
import UIKit
import MapKit
class DetailViewController : UIViewController {
@IBOutlet weak var mapView: MKMapView!
var selectedLocation : LocationModel?
override func viewDidLoad() {
super.viewDidLoad()
}
override func viewDidAppear(animated: Bool) {
// Create coordinates from location lat/long
var poiCoodinates: CLLocationCoordinate2D = CLLocationCoordinate2D();
print(selectedLocation)
print("\(LocationModel())")
poiCoodinates.longitude = CDouble(self.selectedLocation!.longitude!)!
poiCoodinates.latitude = CDouble(self.selectedLocation!.latitude!)!
// Zoom to region
let viewRegion: MKCoordinateRegion = MKCoordinateRegionMakeWithDistance(poiCoodinates, 750, 750)
self.mapView.setRegion(viewRegion, animated: true)
// Plot pin
let pin: MKPointAnnotation = MKPointAnnotation()
pin.coordinate = poiCoodinates
self.mapView.addAnnotation(pin)
//add title to the pin
pin.title = selectedLocation!.name
}
}