swift中闭包的使用(类似与block的做法) 闭包传值
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需要闭包的类
import UIKit //定义闭包类型(特定的函数类型函数类型) typealias InputClosureType = (String) -> Void protocol SecondViewControllerDelegate: NSObjectProtocol{ func fetchBackString(str: String) } class SecondViewController: UIViewController { @IBOutlet weak var inputTextField: UITextField! //接收上个页面传过来的闭包块 var backClosure: InputClosureType? weak var delegate: SecondViewControllerDelegate? override func viewDidLoad() { super.viewDidLoad() // Do any additional setup after loading the view. } @IBAction func tapBackButton(sender: UIButton) { if self.backClosure != nil { if let tempString = self.inputTextField.text { self.backClosure!(tempString) } } self.navigationController?.popViewControllerAnimated(true) } @IBAction func delegateBackMethod(sender: UIButton) { if self.delegate != nil { if let tempString = self.inputTextField.text { delegate!.fetchBackString("代理返回数据:\(tempString)") } } self.navigationController?.popViewControllerAnimated(true) } override func didReceiveMemoryWarning() { super.didReceiveMemoryWarning() // Dispose of any resources that can be recreated. } }
在另一个类里调用闭包
import UIKit class FirstViewController: UIViewController, SecondViewControllerDelegate { @IBOutlet weak var showTextLabel: UILabel! @IBOutlet weak var showDelegateTextLabel: UILabel! override func viewDidLoad() { super.viewDidLoad() // Do any additional setup after loading the view. } //点击按钮跳转到SecondViewController @IBAction func tapGoSecondViewController(sender: UIButton) { //从storyboard上加载SecondViewController let secondVC = UIStoryboard(name: "Main", bundle: NSBundle.mainBundle()).instantiateViewControllerWithIdentifier("secondViewController") as! SecondViewController //实现回调,获取回调回来的值 (闭包) secondVC.backClosure = { (backStr: String) -> Void in self.showTextLabel.text = backStr } secondVC.delegate = self //跳转到SecondViewController self.navigationController?.pushViewController(secondVC, animated: true) } //MARK: - SecondViewControllerDelegate(代理) func fetchBackString(str: String) { self.showDelegateTextLabel.text = str } override func didReceiveMemoryWarning() { super.didReceiveMemoryWarning() // Dispose of any resources that can be recreated. } }
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