Question

 UIView.animateWithDuration(5, animations: {
        myLabel.textColor = UIColor.redColor()
    })

标签文字颜色立即改变

Answer 1

试试这个

[UIView transitionWithView:myLabel duration:0.25 options:UIViewAnimationOptionTransitionCrossDissolve animations:^{
    label.textColor = [UIColor redColor];
} completion:^(BOOL finished) {
}];

Answer 2

我写下了Objective-C和Swift

的代码

动画类型

typedef NS_OPTIONS(NSUInteger, UIViewAnimationOptions) {
UIViewAnimationOptionCurveEaseInOut            = 0 << 16, // default
UIViewAnimationOptionCurveEaseIn               = 1 << 16,
UIViewAnimationOptionCurveEaseOut              = 2 << 16,
UIViewAnimationOptionCurveLinear               = 3 << 16,

UIViewAnimationOptionTransitionNone            = 0 << 20, // default
UIViewAnimationOptionTransitionFlipFromLeft    = 1 << 20,
UIViewAnimationOptionTransitionFlipFromRight   = 2 << 20,
UIViewAnimationOptionTransitionCurlUp          = 3 << 20,
UIViewAnimationOptionTransitionCurlDown        = 4 << 20,
UIViewAnimationOptionTransitionCrossDissolve   = 5 << 20,
UIViewAnimationOptionTransitionFlipFromTop     = 6 << 20,
UIViewAnimationOptionTransitionFlipFromBottom  = 7 << 20,
} NS_ENUM_AVAILABLE_IOS(4_0);

Objective-C

的

编码

[UIView transitionWithView:myLabel duration:0.20 options: UIViewAnimationOptionTransitionFlipFromBottom animations:^{
myLabel.textColor = [UIColor redColor];

} completion:^(BOOL finished) {
}];

Swift

的

编码

  UIView.transition(with: myLabel, duration: 0.20, options: .transitionFlipFromBottom, animations: {() -> Void in
        self.myLabel.textColor = UIColor.red
    }, completion: {(_ finished: Bool) -> Void in
    })

Answer 3

即使你说接受的答案有效，（1）你需要使用TransitionCrossDissolve代替CurveEaseInOut; （2）在测试时，我注意到在Swift中，似乎你不能在动画制作之前立即添加子视图。（我认为这是一个错误。）

在您的示例中看到myLabel似乎是本地的（因为全局变量必须在块闭包中写为self.myLabel），您很有可能在与动画相同的方法中添加了myLabel子视图，没有延迟。

因此，如果您仍然遇到问题，我建议（1）使myLabel全局和（2）在添加子视图和在该子视图上执行动画之间添加延迟，例如：

    self.view.addSubview(myLabel)
    var timer = NSTimer.scheduledTimerWithTimeInterval(0.01, target: self, selector: "animate", userInfo: nil, repeats: false)
}

func animate() {
    UIView.transitionWithView(myLabel, duration: 5.0, options: UIViewAnimationOptions.TransitionCrossDissolve, animations: {
        self.myLabel.textColor = UIColor.redColor()
        }, completion:nil)
}

是否可以为UILabel文本颜色变化制作动画？

3 个答案: