我正在制作一本关于书的应用程序。 在应用程序中， 我想通过获取ISBN（条形码）
来使应用程序自动填充书籍信息有2个班级。 一个是'UploadMain'，另一个是'ScanView'
我可以通过扫描获得ISBN， 但我有一个问题是将数据从ScanView传递到UploadMain。
在ScanView中，我使用了可选的Binding，如下所示
if let UploadVC = self.storyboard?.instantiateViewControllerWithIdentifier("UploadMain") as? UploadMain {
UploadVC.ISBNstring = self.detectionString!
}
UploadMain类代码
override func viewDidLoad(){
super.viewDidLoad()
ISBN.delegate = self
}
override func viewWillAppear(animated: Bool){
ISBN.text = ISBNstring
}
我不知道我的代码是什么问题。
UploadMain
的完整代码import UIKit
import Foundation
class UploadMain: UIViewController,UITextFieldDelegate {
var ISBNstring: String = ""
var TitleString: String = ""
var AuthorString: String = ""
var PubString: String = ""
var PriceSting: String = ""
@IBOutlet weak var ISBN: UITextField!
@IBOutlet weak var bookTitle: UITextField!
@IBOutlet weak var bookAuthor: UITextField!
@IBOutlet weak var bookPub: UITextField!
@IBOutlet weak var bookPrice: UITextField!
override func viewDidLoad(){
super.viewDidLoad()
ISBN.delegate = self
}
override func viewWillAppear(animated: Bool){
ISBN.text = ISBNstring
}
@IBAction func Upload(sender: AnyObject) {
dismissViewControllerAnimated(true, completion: nil)
}
}
ScanView类
import UIKit
import AVFoundation
import Foundation
class ScanView : UIViewController, AVCaptureMetadataOutputObjectsDelegate {
let session : AVCaptureSession = AVCaptureSession()
var previewLayer : AVCaptureVideoPreviewLayer!
var detectionString : String!
let apiKey : String = "---------dddddd"
override func viewDidLoad() {
super.viewDidLoad()
// For the sake of discussion this is the camera
let device = AVCaptureDevice.defaultDeviceWithMediaType(AVMediaTypeVideo)
// Create a nilable NSError to hand off to the next method.
// Make sure to use the "var" keyword and not "let"
var error : NSError? = nil
var input: AVCaptureDeviceInput = AVCaptureDeviceInput()
do {
input = try AVCaptureDeviceInput(device: device) as AVCaptureDeviceInput
} catch let myJSONError {
print(myJSONError)
}
// If our input is not nil then add it to the session, otherwise we're kind of done!
if input != AVCaptureDeviceInput() {
session.addInput(input)
}
else {
// This is fine for a demo, do something real with this in your app. :)
print(error)
}
let output = AVCaptureMetadataOutput()
output.setMetadataObjectsDelegate(self, queue: dispatch_get_main_queue())
session.addOutput(output)
output.metadataObjectTypes = output.availableMetadataObjectTypes
previewLayer = AVCaptureVideoPreviewLayer(session: session)
previewLayer.frame = self.view.bounds
previewLayer.videoGravity = AVLayerVideoGravityResizeAspectFill
self.view.layer.addSublayer(previewLayer)
// Start the scanner. You'll have to end it yourself later.
session.startRunning()
}
// This is called when we find a known barcode type with the camera.
func captureOutput(captureOutput: AVCaptureOutput!, didOutputMetadataObjects metadataObjects: [AnyObject]!, fromConnection connection: AVCaptureConnection!) {
var highlightViewRect = CGRectZero
var barCodeObject : AVMetadataObject!
let barCodeTypes = [AVMetadataObjectTypeEAN13Code, AVMetadataObjectTypeEAN8Code]
// The scanner is capable of capturing multiple 2-dimensional barcodes in one scan.
for metadata in metadataObjects {
for barcodeType in barCodeTypes {
if metadata.type == barcodeType {
barCodeObject = self.previewLayer.transformedMetadataObjectForMetadataObject(metadata as! AVMetadataMachineReadableCodeObject)
highlightViewRect = barCodeObject.bounds
detectionString = (metadata as! AVMetadataMachineReadableCodeObject).stringValue
self.session.stopRunning()
self.alert(detectionString)
// Daum Book API 호출
let apiURI = NSURL(string: "https://apis.daum.net/search/book?apikey=\(apiKey)&q=\(detectionString)&searchType=isbn&output=json")
let apidata : NSData? = NSData(contentsOfURL: apiURI!)
NSLog("API Result = %@", NSString(data: apidata!, encoding: NSUTF8StringEncoding)!)
**if let UploadVC = self.storyboard?.instantiateViewControllerWithIdentifier("UploadMain") as? UploadMain {
UploadVC.ISBNstring = self.detectionString!
}**
break
}
}
}
print(detectionString)
self.navigationController?.popViewControllerAnimated(true)
}
func alert(Code: String){
let actionSheet:UIAlertController = UIAlertController(title: "Barcode", message: "\(Code)", preferredStyle: UIAlertControllerStyle.Alert)
// for alert add .Alert instead of .Action Sheet
// start copy
let firstAlertAction:UIAlertAction = UIAlertAction(title: "OK", style: UIAlertActionStyle.Default, handler:
{
(alertAction:UIAlertAction!) in
// action when pressed
self.session.startRunning()
})
actionSheet.addAction(firstAlertAction)
}
}
答案 0 :(得分：1)
在ScanView中，您正在创建UploadMain的新实例，这在窗口层次结构中不可用，因此UploadMain无法使用该数据。要解决您的问题，您需要创建一个protocol并将该协议的委托传递给ScanView。因此，像这样创建一个protocol。
protocol IsbnDelegate {
func passData(isbnStr: String)
}
现在在UploadMain中继承此协议并覆盖passData中的方法UploadMain，如下所示
class UploadMain: UIViewController,UITextFieldDelegate,IsbnDelegate {
//your code
//Add this method
func passData(isbnStr: String) {
self.ISBN.text = isbnStr
}
//Also override prepareForSegue like this
override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
let destVC = segue.destinationViewController as! ScanView
destVC.delegate = self
}
}
之后在delegate中创建一个ScanView对象，将此代码更改为ScanView
import UIKit
import AVFoundation
import Foundation
class ScanView : UIViewController, AVCaptureMetadataOutputObjectsDelegate {
let session : AVCaptureSession = AVCaptureSession()
var previewLayer : AVCaptureVideoPreviewLayer!
var detectionString : String!
let apiKey : String = "---------dddddd"
var delegate: IsbnDelegate?
override func viewDidLoad() {
super.viewDidLoad()
// For the sake of discussion this is the camera
let device = AVCaptureDevice.defaultDeviceWithMediaType(AVMediaTypeVideo)
// Create a nilable NSError to hand off to the next method.
// Make sure to use the "var" keyword and not "let"
var error : NSError? = nil
var input: AVCaptureDeviceInput = AVCaptureDeviceInput()
do {
input = try AVCaptureDeviceInput(device: device) as AVCaptureDeviceInput
} catch let myJSONError {
print(myJSONError)
}
// If our input is not nil then add it to the session, otherwise we're kind of done!
if input != AVCaptureDeviceInput() {
session.addInput(input)
}
else {
// This is fine for a demo, do something real with this in your app. :)
print(error)
}
let output = AVCaptureMetadataOutput()
output.setMetadataObjectsDelegate(self, queue: dispatch_get_main_queue())
session.addOutput(output)
output.metadataObjectTypes = output.availableMetadataObjectTypes
previewLayer = AVCaptureVideoPreviewLayer(session: session)
previewLayer.frame = self.view.bounds
previewLayer.videoGravity = AVLayerVideoGravityResizeAspectFill
self.view.layer.addSublayer(previewLayer)
// Start the scanner. You'll have to end it yourself later.
session.startRunning()
}
// This is called when we find a known barcode type with the camera.
func captureOutput(captureOutput: AVCaptureOutput!, didOutputMetadataObjects metadataObjects: [AnyObject]!, fromConnection connection: AVCaptureConnection!) {
var highlightViewRect = CGRectZero
var barCodeObject : AVMetadataObject!
let barCodeTypes = [AVMetadataObjectTypeEAN13Code, AVMetadataObjectTypeEAN8Code]
// The scanner is capable of capturing multiple 2-dimensional barcodes in one scan.
for metadata in metadataObjects {
for barcodeType in barCodeTypes {
if metadata.type == barcodeType {
barCodeObject = self.previewLayer.transformedMetadataObjectForMetadataObject(metadata as! AVMetadataMachineReadableCodeObject)
highlightViewRect = barCodeObject.bounds
detectionString = (metadata as! AVMetadataMachineReadableCodeObject).stringValue
self.session.stopRunning()
self.alert(detectionString)
// Daum Book API 호출
let apiURI = NSURL(string: "https://apis.daum.net/search/book?apikey=\(apiKey)&q=\(detectionString)&searchType=isbn&output=json")
let apidata : NSData? = NSData(contentsOfURL: apiURI!)
NSLog("API Result = %@", NSString(data: apidata!, encoding: NSUTF8StringEncoding)!)
//Here We are passing the data of your ScanView to UploadMain
self.delegate.passData(self.detectionString!)
break
}
}
}
print(detectionString)
self.navigationController?.popViewControllerAnimated(true)
}
func alert(Code: String){
let actionSheet:UIAlertController = UIAlertController(title: "Barcode", message: "\(Code)", preferredStyle: UIAlertControllerStyle.Alert)
// for alert add .Alert instead of .Action Sheet
// start copy
let firstAlertAction:UIAlertAction = UIAlertAction(title: "OK", style: UIAlertActionStyle.Default, handler:
{
(alertAction:UIAlertAction!) in
// action when pressed
self.session.startRunning()
})
actionSheet.addAction(firstAlertAction)
}
}
有关protcol的详细信息，请点击此链接
1）Apple Documentation
2）Tutorial 1
3）Tutorial 2
希望这会对你有所帮助。
答案 1 :(得分：0)