我有一个背景颜色为灰色的 UILabel。
我想要在这个标签上产生闪烁效果，比如它应该变成一点白色然后变成灰色，并且它应该一直发生，直到我以编程方式将其关闭。
任何线索如何实现这一点？
【问题讨论】：
标签： ios objective-c cocoa-touch uiview uilabel
您可以在一个块内执行此操作：
self.yourLabel.alpha = 1;
[UIView animateWithDuration:1.5 delay:0.5 options:UIViewAnimationOptionRepeat | UIViewAnimationOptionAutoreverse animations:^{
self.yourLabel.alpha = 0;
} completion:nil];
所以你不需要第二种方法。
【讨论】：
[self.yourLabel.layer removeAllAnimations] 停止动画。
.alpha = 1;第一次在动画块.alpha = 0;这将避免在动画开始时奇怪的闪烁。
斯威夫特 3
extension UILabel {
func startBlink() {
UIView.animate(withDuration: 0.8,
delay:0.0,
options:[.allowUserInteraction, .curveEaseInOut, .autoreverse, .repeat],
animations: { self.alpha = 0 },
completion: nil)
}
func stopBlink() {
layer.removeAllAnimations()
alpha = 1
}
}
【讨论】：
使用NSTimer
NSTimer *timer = [NSTimer
scheduledTimerWithTimeInterval:(NSTimeInterval)(1.0)
target:self
selector:@selector(blink)
userInfo:nil
repeats:TRUE];
BOOL blinkStatus = NO;
在你的眨眼功能中
-(void)blink{
if(blinkStatus == NO){
yourLabel.backgroundColor = [UIColor whiteColor];
blinkStatus = YES;
}else {
yourLabel.backgroundColor = [UIColor grayColor];
blinkStatus = NO;
}
}
【讨论】：
您可以简单地对 UILabel 类进行扩展，以支持 blinking 效果。我不认为使用计时器是正确的方法，因为你不会有任何淡入淡出效果。
这是 Swift 的方法：
extension UILabel {
func blink() {
self.alpha = 0.0;
UIView.animateWithDuration(0.8, //Time duration you want,
delay: 0.0,
options: [.CurveEaseInOut, .Autoreverse, .Repeat],
animations: { [weak self] in self?.alpha = 1.0 },
completion: { [weak self] _ in self?.alpha = 0.0 })
}
}
斯威夫特 3：
extension UILabel {
func blink() {
self.alpha = 0.0;
UIView.animate(withDuration: 0.8, //Time duration you want,
delay: 0.0,
options: [.curveEaseInOut, .autoreverse, .repeat],
animations: { [weak self] in self?.alpha = 1.0 },
completion: { [weak self] _ in self?.alpha = 0.0 })
}
}
EDIT Swift 3：适用于几乎所有视图
extension UIView {
func blink() {
self.alpha = 0.0;
UIView.animate(withDuration: 0.8, //Time duration you want,
delay: 0.0,
options: [.curveEaseInOut, .autoreverse, .repeat],
animations: { [weak self] in self?.alpha = 1.0 },
completion: { [weak self] _ in self?.alpha = 0.0 })
}
}
【讨论】：
一种不同的方法，但有效。仅闪烁 3 秒
extension UIView {
func blink() {
let animation = CABasicAnimation(keyPath: "opacity")
animation.isRemovedOnCompletion = false
animation.fromValue = 1
animation.toValue = 0
animation.duration = 0.8
animation.autoreverses = true
animation.repeatCount = 3
animation.beginTime = CACurrentMediaTime() + 0.5
self.layer.add(animation, forKey: nil)
}
}
【讨论】：
宁可使用视图动画。它使它非常简单并且易于控制。试试这个：
self.yourLabel.alpha = 1.0f;
[UIView animateWithDuration:0.12
delay:0.0
options:UIViewAnimationOptionCurveEaseInOut |
UIViewAnimationOptionRepeat |
UIViewAnimationOptionAutoreverse |
UIViewAnimationOptionAllowUserInteraction
animations:^{
self.yourLabel.alpha = 0.0f;
}
completion:^(BOOL finished){
// Do nothing
}];
您可以调整这些值以获得不同的效果，例如，更改 animateWithDuration 将设置闪烁速度。此外，您可以在从 UIView 继承的任何东西上使用它，例如按钮、标签、自定义视图等。
【讨论】：
调整 Krishnabhadra 答案以提供更好的眨眼效果
声明一个类变量bool blinkStatus;
并粘贴下面给出的代码
NSTimer *yourtimer = [NSTimer scheduledTimerWithTimeInterval:(NSTimeInterval)(10.0 / 60.0) target:self selector:@selector(blink) userInfo:nil repeats:TRUE];
blinkStatus = FALSE;
-(void)blink{
if(blinkStatus == FALSE){
yourLabel.hidden=NO;
blinkStatus = TRUE;
}else {
yourLabel.hidden=YES;
blinkStatus = FALSE;
}
}
【讨论】：
-(void) startBlinkingLabel:(UILabel *)label
{
label.alpha =1.0f;
[UIView animateWithDuration:0.32
delay:0.0
options: UIViewAnimationOptionAutoreverse |UIViewAnimationOptionRepeat | UIViewAnimationOptionCurveEaseInOut | UIViewAnimationOptionAllowUserInteraction |UIViewAnimationOptionBeginFromCurrentState
animations:^{
label.alpha = 0.0f;
}
completion:^(BOOL finished){
if (finished) {
}
}];
}
-(void) stopBlinkingLabel:(UILabel *)label
{
// REMOVE ANIMATION
[label.layer removeAnimationForKey:@"opacity"];
label.alpha = 1.0f;
}
【讨论】：
尝试使用 swift 并使用多个选项时卡住了，但这似乎效果很好：
self.cursorLabel.alpha = 1
UIView.animate(withDuration: 0.7, delay: 0.0, options: [.repeat, .autoreverse, .curveEaseInOut], animations: {
self.cursorLabel.alpha = 0
}, completion: nil)
【讨论】：
这就是它对我的工作方式。我改编了@flex_elektro_deimling 的答案
第一个参数 UIView.animateWithDuration 是动画的总时间（在我的例子中我设置为 0.5），你可以在第一个和第二个（延迟）上设置不同的值来改变闪烁速度。
self.YOURLABEL.alpha = 0;
UIView.animateWithDuration(
0.5,
delay: 0.2,
options: UIViewAnimationOptions.Repeat | UIViewAnimationOptions.Autoreverse, animations: {
self.YOURLABEL.alpha = 1
},
completion:nil)
【讨论】：
我的基于Flex Elektro Deimling's answer的swift版本：
private func startTimeBlinkAnimation(start: Bool) {
if start {
timeContainerView.alpha = 1
UIView.animateWithDuration(0.6, delay: 0.3, options:[.Repeat, .Autoreverse], animations: { _ in
self.timeContainerView.alpha = 0
}, completion: nil)
}
else {
timeContainerView.alpha = 1
timeContainerView.layer.removeAllAnimations()
}
}
【讨论】：
int count;
NSTimer *timer;
timer= [NSTimer
scheduledTimerWithTimeInterval:(NSTimeInterval)(0.5)
target:self
selector:@selector(animationStart)
userInfo:nil
repeats:TRUE];
-(void)animationStart{
switch (count) {
case 0:
//205 198 115
count++;
lbl.textColor=[UIColor colorWithRed:205.0f/255.0f green:198.0f/255.0f blue:115.0f/255.0f alpha:1];
break;
case 1:
count++;
//205 198 115 56 142 142
lbl.textColor=[UIColor colorWithRed:56.0f/255.0f green:142.0f/255.0f blue:142.0f/255.0f alpha:1];
break;
case 2:
count++;
//205 198 115
lbl.textColor=[UIColor colorWithRed:205.0f/255.0f green:205.0f/255.0f blue:0.0f/255.0f alpha:1];
break;
case 3:
count++;
//205 198 115 84 255 159
lbl.textColor=[UIColor colorWithRed:84.0f/255.0f green:255.0f/255.0f blue:159.0f/255.0f alpha:1];
break;
case 4:
count++;
//205 198 115 255 193 37
lbl.textColor=[UIColor colorWithRed:255.0f/255.0f green:193.0f/255.0f blue:37.0f/255.0f alpha:1];
break;
case 5:
count++;
//205 198 115 205 200 177
lbl.textColor=[UIColor colorWithRed:205.0f/255.0f green:200.0f/255.0f blue:117.0f/255.0f alpha:1];
break;
case 6:
count++;
//205 198 115 255 228 181
lbl.textColor=[UIColor colorWithRed:255.0f/255.0f green:228.0f/255.0f blue:181.0f/255.0f alpha:1];
break;
case 7:
count++;
//205 198 115 233 150 122
lbl.textColor=[UIColor colorWithRed:233.0f/255.0f green:150.0f/255.0f blue:122.0f/255.0f alpha:1];
break;
case 8:
count++;
//205 198 115 233 150 122
lbl.textColor=[UIColor colorWithRed:255.0f/255.0f green:200.0f/255.0f blue:200.0f/255.0f alpha:1];
break;
case 9:
count=0;
//205 198 115 255 99 71 255 48 48
lbl.textColor=[UIColor colorWithRed:255.0f/255.0f green:48.0f/255.0f blue:48.0f/255.0f alpha:1];
break;
default:
break;
}
}
【讨论】：
这是我在 Swift 4.0 中的解决方案，带有任何 UIVIew 的扩展名
extension UIView{
func blink() {
self.alpha = 0.2
UIView.animate(withDuration: 1,
delay: 0.0,
options: [.curveLinear,
.repeat,
.autoreverse],
animations: { self.alpha = 1.0 },
completion: nil)
}
}
【讨论】：
对于 Swift 3+，在此处所有出色答案的基础上，我最终进行了一些调整，使我获得了平滑的闪烁效果，在给定数量的循环后自动停止。
extension UIView {
func blink(duration: Double=0.5, repeatCount: Int=2) {
self.alpha = 0.0;
UIView.animate(withDuration: duration,
delay: 0.0,
options: [.curveEaseInOut, .autoreverse, .repeat],
animations: { [weak self] in
UIView.setAnimationRepeatCount(Float(repeatCount) + 0.5)
self?.alpha = 1.0
}
)
}
}
【讨论】：