我正在尝试以编程方式构建UI。如何使该动作起作用?我正在用Swift开发。
viewDidLoad中的代码:
override func viewDidLoad() { super.viewDidLoad() // Do any additional setup after loading the view, typically from a nib. let myFirstLabel = UILabel() let myFirstButton = UIButton() myFirstLabel.text = "I made a label on the screen #toogood4you" myFirstLabel.font = UIFont(name: "MarkerFelt-Thin", size: 45) myFirstLabel.textColor = UIColor.redColor() myFirstLabel.textAlignment = .Center myFirstLabel.numberOfLines = 5 myFirstLabel.frame = CGRectMake(15, 54, 300, 500) myFirstButton.setTitle("✸", forState: .Normal) myFirstButton.setTitleColor(UIColor.blueColor(), forState: .Normal) myFirstButton.frame = CGRectMake(15, -50, 300, 500) myFirstButton.addTarget(self, action: "pressed", forControlEvents: .TouchUpInside) self.view.addSubview(myFirstLabel) self.view.addSubview(myFirstButton) } func pressed(sender: UIButton!) { var alertView = UIAlertView(); alertView.addButtonWithTitle("Ok"); alertView.title = "title"; alertView.message = "message"; alertView.show(); }
您只是在选择器名称的末尾缺少冒号。因为按下需要一个参数,所以冒号必须在该位置。而且,您按下的函数不应嵌套在viewDidLoad中。
override func viewDidLoad() { super.viewDidLoad() // Do any additional setup after loading the view, typically from a nib. let myFirstLabel = UILabel() let myFirstButton = UIButton() myFirstLabel.text = "I made a label on the screen #toogood4you" myFirstLabel.font = UIFont(name: "MarkerFelt-Thin", size: 45) myFirstLabel.textColor = UIColor.redColor() myFirstLabel.textAlignment = .Center myFirstLabel.numberOfLines = 5 myFirstLabel.frame = CGRectMake(15, 54, 300, 500) myFirstButton.setTitle("✸", forState: .Normal) myFirstButton.setTitleColor(UIColor.blueColor(), forState: .Normal) myFirstButton.frame = CGRectMake(15, -50, 300, 500) myFirstButton.addTarget(self, action: #selector(myClass.pressed(_:)), forControlEvents: .TouchUpInside) self.view.addSubview(myFirstLabel) self.view.addSubview(myFirstButton) } @objc func pressed(sender: UIButton!) { var alertView = UIAlertView() alertView.addButtonWithTitle("Ok") alertView.title = "title" alertView.message = "message" alertView.show() }
编辑:更新以反映Swift 2.2中的最佳实践。应该使用#selector()而不是不推荐使用的文字字符串。