我正在将一个新的文本值设置为UILabel. 目前，新文本看起来很好。但是，我想在新文本出现时添加一些动画。我想知道我可以做些什么来为新文本的外观设置动画。
问问题
110897 次
14 回答
199
我想知道它是否有效，而且效果很好！
Objective-C
[UIView transitionWithView:self.label
duration:0.25f
options:UIViewAnimationOptionTransitionCrossDissolve
animations:^{
self.label.text = rand() % 2 ? @"Nice nice!" : @"Well done!";
} completion:nil];
斯威夫特 3, 4, 5
UIView.transition(with: label,
duration: 0.25,
options: .transitionCrossDissolve,
animations: { [weak self] in
self?.label.text = (arc4random()() % 2 == 0) ? "One" : "Two"
}, completion: nil)
于 2014-09-17T12:43:57.910 回答
165
Objective-C
为了实现真正的交叉溶解过渡（旧标签淡出而新标签淡入），您不希望淡入淡出不可见。即使文本未更改，也会导致不必要的闪烁。
请改用此方法：
CATransition *animation = [CATransition animation];
animation.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseInEaseOut];
animation.type = kCATransitionFade;
animation.duration = 0.75;
[aLabel.layer addAnimation:animation forKey:@"kCATransitionFade"];
// This will fade:
aLabel.text = "New"
另请参阅： 两个数字之间的动画 UILabel 文本？
iOS 10、9、8 中的演示：
在iOS 10 到 8.0上使用Xcode 8.2.1 & 7.1、ObjectiveC进行测试。
► 要下载完整项目，请在Swift Recipes中搜索SO-3073520。
于 2013-05-03T20:55:41.913 回答
140
斯威夫特 4
淡化 UILabel （或任何 UIView ）的正确方法是使用Core Animation Transition. 这不会闪烁，如果内容不变，它也不会变黑。
一个可移植且干净的解决方案是Extension在 Swift 中使用 a （调用之前更改的可见元素）
// Usage: insert view.fadeTransition right before changing content
extension UIView {
func fadeTransition(_ duration:CFTimeInterval) {
let animation = CATransition()
animation.timingFunction = CAMediaTimingFunction(name:
CAMediaTimingFunctionName.easeInEaseOut)
animation.type = CATransitionType.fade
animation.duration = duration
layer.add(animation, forKey: CATransitionType.fade.rawValue)
}
}
调用如下所示：
// This will fade
aLabel.fadeTransition(0.4)
aLabel.text = "text"
► 在GitHub 上找到此解决方案，并在Swift Recipes上找到更多详细信息。
于 2014-12-25T08:26:14.097 回答
24
从 iOS4 开始，显然可以用块来完成：
[UIView animateWithDuration:1.0
animations:^{
label.alpha = 0.0f;
label.text = newText;
label.alpha = 1.0f;
}];
于 2012-06-28T19:36:14.977 回答
17
这是使这项工作的代码。
[UIView beginAnimations:@"animateText" context:nil];
[UIView setAnimationCurve:UIViewAnimationCurveEaseIn];
[UIView setAnimationDuration:1.0f];
[self.lbl setAlpha:0];
[self.lbl setText:@"New Text";
[self.lbl setAlpha:1];
[UIView commitAnimations];
于 2010-06-18T23:28:57.907 回答
5
SwiftArchitect 上述解决方案的 Swift 4.2 版本（效果很好）：
// Usage: insert view.fadeTransition right before changing content
extension UIView {
func fadeTransition(_ duration:CFTimeInterval) {
let animation = CATransition()
animation.timingFunction = CAMediaTimingFunction(name: CAMediaTimingFunctionName.easeInEaseOut)
animation.type = CATransitionType.fade
animation.duration = duration
layer.add(animation, forKey: CATransitionType.fade.rawValue)
}
}
调用：
// This will fade
aLabel.fadeTransition(0.4)
aLabel.text = "text"
于 2018-09-26T10:50:27.513 回答
5
UILabel 扩展解决方案
extension UILabel{
func animation(typing value:String,duration: Double){
let characters = value.map { $0 }
var index = 0
Timer.scheduledTimer(withTimeInterval: duration, repeats: true, block: { [weak self] timer in
if index < value.count {
let char = characters[index]
self?.text! += "\(char)"
index += 1
} else {
timer.invalidate()
}
})
}
func textWithAnimation(text:String,duration:CFTimeInterval){
fadeTransition(duration)
self.text = text
}
//followed from @Chris and @winnie-ru
func fadeTransition(_ duration:CFTimeInterval) {
let animation = CATransition()
animation.timingFunction = CAMediaTimingFunction(name:
CAMediaTimingFunctionName.easeInEaseOut)
animation.type = CATransitionType.fade
animation.duration = duration
layer.add(animation, forKey: CATransitionType.fade.rawValue)
}
}
简单地调用函数
uiLabel.textWithAnimation(text: "text you want to replace", duration: 0.2)
感谢所有提示的家伙。希望这将有助于长期
于 2019-02-21T17:08:00.813 回答
4
斯威夫特 2.0：
UIView.transitionWithView(self.view, duration: 1.0, options: UIViewAnimationOptions.TransitionCrossDissolve, animations: {
self.sampleLabel.text = "Animation Fade1"
}, completion: { (finished: Bool) -> () in
self.sampleLabel.text = "Animation Fade - 34"
})
或者
UIView.animateWithDuration(0.2, animations: {
self.sampleLabel.alpha = 1
}, completion: {
(value: Bool) in
self.sampleLabel.alpha = 0.2
})
于 2016-02-11T09:00:16.677 回答
4
使用 Swift 5，您可以选择以下两个 Playground 代码示例之一，以便UILabel使用一些交叉溶解动画为您的文本更改设置动画。
#1。使用UIView的transition(with:duration:options:animations:completion:)类方法
import UIKit
import PlaygroundSupport
class ViewController: UIViewController {
let label = UILabel()
override func viewDidLoad() {
super.viewDidLoad()
label.text = "Car"
view.backgroundColor = .white
view.addSubview(label)
label.translatesAutoresizingMaskIntoConstraints = false
label.centerXAnchor.constraint(equalTo: view.centerXAnchor).isActive = true
label.centerYAnchor.constraint(equalTo: view.centerYAnchor).isActive = true
let tapGesture = UITapGestureRecognizer(target: self, action: #selector(toggle(_:)))
view.addGestureRecognizer(tapGesture)
}
@objc func toggle(_ sender: UITapGestureRecognizer) {
let animation = {
self.label.text = self.label.text == "Car" ? "Plane" : "Car"
}
UIView.transition(with: label, duration: 2, options: .transitionCrossDissolve, animations: animation, completion: nil)
}
}
let controller = ViewController()
PlaygroundPage.current.liveView = controller
#2。使用CATransitionandCALayer的add(_:forKey:)方法
import UIKit
import PlaygroundSupport
class ViewController: UIViewController {
let label = UILabel()
let animation = CATransition()
override func viewDidLoad() {
super.viewDidLoad()
label.text = "Car"
animation.timingFunction = CAMediaTimingFunction(name: CAMediaTimingFunctionName.easeInEaseOut)
// animation.type = CATransitionType.fade // default is fade
animation.duration = 2
view.backgroundColor = .white
view.addSubview(label)
label.translatesAutoresizingMaskIntoConstraints = false
label.centerXAnchor.constraint(equalTo: view.centerXAnchor).isActive = true
label.centerYAnchor.constraint(equalTo: view.centerYAnchor).isActive = true
let tapGesture = UITapGestureRecognizer(target: self, action: #selector(toggle(_:)))
view.addGestureRecognizer(tapGesture)
}
@objc func toggle(_ sender: UITapGestureRecognizer) {
label.layer.add(animation, forKey: nil) // The special key kCATransition is automatically used for transition animations
label.text = label.text == "Car" ? "Plane" : "Car"
}
}
let controller = ViewController()
PlaygroundPage.current.liveView = controller
于 2016-12-11T23:42:17.230 回答
4
动画的duration和timingFunction属性可以省略，在这种情况下，它们将分别采用默认值0.25和.curveEaseInEaseOut。
let animation = CATransition()
label.layer.add(animation, forKey: nil)
label.text = "New text"
和写这个是一样的：
let animation = CATransition()
animation.duration = 0.25
animation.timingFunction = .curveEaseInEaseOut
label.layer.add(animation, forKey: nil)
label.text = "New text"
于 2019-04-07T15:17:43.243 回答
3
Swift 4.2 解决方案（采用 4.0 答案并更新新枚举以进行编译）
extension UIView {
func fadeTransition(_ duration:CFTimeInterval) {
let animation = CATransition()
animation.timingFunction = CAMediaTimingFunction(name:
CAMediaTimingFunctionName.easeInEaseOut)
animation.type = CATransitionType.fade
animation.duration = duration
layer.add(animation, forKey: CATransitionType.fade.rawValue)
}
}
func updateLabel() {
myLabel.fadeTransition(0.4)
myLabel.text = "Hello World"
}
于 2019-01-25T15:01:32.873 回答
1
这是基于@SwiftArchitect 代码的C# UIView 扩展方法。当涉及自动布局并且控件需要根据标签的文本移动时，此调用代码使用标签的Superview作为过渡视图而不是标签本身。我为动作添加了一个 lambda 表达式以使其更加封装。
public static void FadeTransition( this UIView AView, double ADuration, Action AAction )
{
CATransition transition = new CATransition();
transition.Duration = ADuration;
transition.TimingFunction = CAMediaTimingFunction.FromName( CAMediaTimingFunction.Linear );
transition.Type = CATransition.TransitionFade;
AView.Layer.AddAnimation( transition, transition.Type );
AAction();
}
调用代码：
labelSuperview.FadeTransition( 0.5d, () =>
{
if ( condition )
label.Text = "Value 1";
else
label.Text = "Value 2";
} );
于 2016-08-09T04:58:56.043 回答
1
还有另一种解决方案可以实现这一目标。它被描述为here。这个想法是通过以下方式子类化UILabel和覆盖函数：action(for:forKey:)
class LabelWithAnimatedText: UILabel {
override var text: String? {
didSet {
self.layer.setValue(self.text, forKey: "text")
}
}
override func action(for layer: CALayer, forKey event: String) -> CAAction? {
if event == "text" {
if let action = self.action(for: layer, forKey: "backgroundColor") as? CAAnimation {
let transition = CATransition()
transition.type = kCATransitionFade
//CAMediatiming attributes
transition.beginTime = action.beginTime
transition.duration = action.duration
transition.speed = action.speed
transition.timeOffset = action.timeOffset
transition.repeatCount = action.repeatCount
transition.repeatDuration = action.repeatDuration
transition.autoreverses = action.autoreverses
transition.fillMode = action.fillMode
//CAAnimation attributes
transition.timingFunction = action.timingFunction
transition.delegate = action.delegate
return transition
}
}
return super.action(for: layer, forKey: event)
}
}
使用示例：
// do not forget to set the "Custom Class" IB-property to "LabelWithAnimatedText"
// @IBOutlet weak var myLabel: LabelWithAnimatedText!
// ...
UIView.animate(withDuration: 0.5) {
myLabel.text = "I am animated!"
}
myLabel.text = "I am not animated!"
于 2019-01-28T12:25:31.843 回答
0
如果您想Swift延迟执行此操作，请尝试以下操作：
delay(1.0) {
UIView.transitionWithView(self.introLabel, duration: 0.25, options: [.TransitionCrossDissolve], animations: {
self.yourLabel.text = "2"
}, completion: { finished in
self.delay(1.0) {
UIView.transitionWithView(self.introLabel, duration: 0.25, options: [.TransitionCrossDissolve], animations: {
self.yourLabel.text = "1"
}, completion: { finished in
})
}
})
}
使用 @matt 创建的以下函数 - https://stackoverflow.com/a/24318861/1982051：
func delay(delay:Double, closure:()->()) {
dispatch_after(
dispatch_time(
DISPATCH_TIME_NOW,
Int64(delay * Double(NSEC_PER_SEC))
),
dispatch_get_main_queue(), closure)
}
这将在 Swift 3 中变成这样
func delay(_ delay:Double, closure:()->()) {
let when = DispatchTime.now() + delay
DispatchQueue.main.after(when: when, execute: closure)
}
于 2016-06-29T17:40:25.023 回答