Question

Swift 2.0新手;试图学习它，对动画感兴趣并尝试编写一些代码，一次在屏幕上显示一个消息。

我写了这个，它有效，但是我忍不住可以不用CALayers和/或alpha值做些什么？或者一些有生命的小发明，更快捷的东西;这种感觉＆amp;看起来有点笨重，真的排序1977年。

SELECT DISTINCT A1.license 
FROM Accident A1 
WHERE A1.license IN (SELECT A2.license 
                     FROM Accident A2 
                     WHERE A1.accident-date <> A2.accident-date)

Answer 1

我认为Swiftworthy是主观的，但这是另一个基于你的代码当前如何工作的实现，它将NSTimer包装在Swift类中。

class Timer {
    typealias TimerFunction = (Int)->Bool
    private var handler: TimerFunction
    private var i = 0

    init(interval: NSTimeInterval, handler: TimerFunction) {
        self.handler = handler
        NSTimer.scheduledTimerWithTimeInterval(interval, target: self, selector: "timerFired:", userInfo: nil, repeats: true)
    }

    @objc
    private func timerFired(timer:NSTimer) {
        if !handler(i++) {
            timer.invalidate()
        }
    }
}

class ViewController: UIViewController {
    let text: NSAttributedString = {
        let font = UIFont(name: "Georgia", size: 18.0) ?? UIFont.systemFontOfSize(18.0)
        return NSAttributedString(string: "A long time ago, in a galaxy far, far away ...", attributes: [NSFontAttributeName: font])
    }()

    override func viewDidLoad() {
        super.viewDidLoad()

        let textView = UITextView(frame: CGRect(x: 100, y: 120, width: CGRectGetWidth(self.view.frame), height: CGRectGetWidth(self.view.frame)-20))
        self.view.addSubview(textView)

        let _ = Timer(interval: 0.1) {i -> Bool in
            textView.attributedText = self.text.attributedSubstringFromRange(NSRange(location: 0, length: i+1))
            return i + 1 < self.text.string.characters.count
        }
    }
}

在swift 2.0中一次显示一个字符

1 个答案: