我实际上为这个问题专门创建了一个名为UICountingLabel的类：
http://github.com/dataxpress/UICountingLabel
它允许你指定计数模式是线性的、缓入、缓出还是缓入/缓出。 缓入/缓出会慢慢地开始计数，加速，然后在您指定的任意时间内缓慢结束。
目前它不支持根据当前值设置标签的实际字体大小，但如果有需要，我可能会添加该功能。 我的大多数布局中的标签都没有太多的空间可以增大或缩小，因此我不确定您要如何使用它。 但是，它的行为完全像一个普通标签，因此您也可以自己更改字体大小。
这是 @malex 在 Swift 3 中的答案。
func incrementLabel(to endValue: Int) {
let duration: Double = 2.0 //seconds
DispatchQueue.global().async {
for i in 0 ..< (endValue + 1) {
let sleepTime = UInt32(duration/Double(endValue) * 1000000.0)
usleep(sleepTime)
DispatchQueue.main.async {
self.myLabel.text = "\(i)"
}
}
}
}
然而，我强烈建议您只需从GitHub下载这个类并将其拖入您的项目中，因为我的代码中的时间似乎无法正确调整更低/更高的计数数字。这个类很棒，看起来非常好。请参考这篇Medium文章。
你可以使用GCD将延迟转移到后台线程。
这是一个值动画的例子（从1到100在10秒钟内）
float animationPeriod = 10;
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_HIGH, 0), ^{
for (int i = 1; i < 101; i ++) {
usleep(animationPeriod/100 * 1000000); // sleep in microseconds
dispatch_async(dispatch_get_main_queue(), ^{
yourLabel.text = [NSString stringWithFormat:@"%d", i];
});
}
});
sleep（毫秒）。如果您使用等待时间的参数，您可以通过自定义算法减少它。例如，第一次运行2000毫秒，第二次运行2000毫秒 -（i * 100ms），等等。 - Maarten Kesselaers这样你就可以无阻塞睡眠了！将其贴到UILabel上，它会从当前显示的值开始向上或向下计数，清除非数字字符。如有需要，可将其从Double调整为Int或Float。
yourlabel.countAnimation(upto: 100.0)
another simple alternative
extension UILabel {
func countAnimation(upto: Double) {
let from: Double = text?.replace(string: ",", replacement: ".").components(separatedBy: CharacterSet.init(charactersIn: "-0123456789.").inverted).first.flatMap { Double($0) } ?? 0.0
let steps: Int = 20
let duration = 0.350
let rate = duration / Double(steps)
let diff = upto - from
for i in 0...steps {
DispatchQueue.main.asyncAfter(deadline: .now() + rate * Double(i)) {
self.text = "\(from + diff * (Double(i) / Double(steps)))"
}
}
}
}
func updateGems(diff: Int) {
animateIncrement(diff: diff, index: 0, start: 50)
}
func animateIncrement(diff: Int, index: Int, start: Int) {
if index == diff {return}
gemsLabel.text = "\(start + index)"
DispatchQueue.main.asyncAfter(deadline: .now() + 0.002) {
self.animateIncrement(diff: diff, index: index + 1, start: start)
}
}
以下是我对@Sergio回答的改编:
extension UILabel {
func countAnimation(upto: Double) {
let fromString = text?.replacingOccurrences(of: "Score: ", with: "")
let from: Double = fromString?.replacingOccurrences(of: ",", with: ".")
.components(separatedBy: CharacterSet.init(charactersIn: "-0123456789.").inverted)
.first.flatMap { Double($0) } ?? 0.0
let duration = 0.4
let diff = upto - from
let rate = duration / diff
for item in 0...Int(diff) {
DispatchQueue.main.asyncAfter(deadline: .now() + rate * Double(item)) {
self.text = "Score: \(Int(from + diff * (Double(item) / diff)))"
}
}
}
}
所需步骤数量基于起始值和结束值之间的差异。
Swift 4 代码：
let animationPeriod: Float = 1
DispatchQueue.global(qos: .default).async(execute: {
for i in 1..<Int(endValue) {
usleep(useconds_t(animationPeriod / 10 * 10000)) // sleep in microseconds
DispatchQueue.main.async(execute: {
self.lbl.text = "\(i+1)"
})
}
})
func animateCountLabel(to userCount: Int) {
countLabel.text = " "
let countStart: Int = userCount - 10
let countEnd: Int = userCount
DispatchQueue.global(qos: .default).async { [weak self] in
for i in (countStart...countEnd) {
let delayTime = UInt64(pow(2, (Float(i) - Float(countStart))))
usleep(useconds_t( delayTime * 1300 )) // sleep in microseconds
DispatchQueue.main.async { [weak self] in
self?.countLabel.text = "\(i)"
}
}
}
}
这是我是如何做到的：
- (void)setupAndStartCounter:(CGFloat)duration {
NSUInteger step = 3;//use your own logic here to define the step.
NSUInteger remainder = numberYouWantToCount%step;//for me it was 30
if (step < remainder) {
remainder = remainder%step;
}
self.aTimer = [self getTimer:[self getInvocation:@selector(animateLabel:increment:) arguments:[NSMutableArray arrayWithObjects:[NSNumber numberWithInteger:remainder], [NSNumber numberWithInteger:step], nil]] timeInterval:(duration * (step/(float) numberYouWantToCountTo)) willRepeat:YES];
[self addTimerToRunLoop:self.aTimer];
}
- (void)animateLabel:(NSNumber*)remainder increment:(NSNumber*)increment {
NSInteger finish = finalValue;
if ([self.aLabel.text integerValue] <= (finish) && ([self.aLabel.text integerValue] + [increment integerValue]<= (finish))) {
self.aLabel.text = [NSString stringWithFormat:@"%lu",(unsigned long)([self.aLabel.text integerValue] + [increment integerValue])];
}else{
self.aLabel.text = [NSString stringWithFormat:@"%lu",(unsigned long)([self.aLabel.text integerValue] + [remainder integerValue])];
[self.aTimer invalidate];
self.aTimer = nil;
}
}
#pragma mark -
#pragma mark Timer related Functions
- (NSTimer*)getTimer:(NSInvocation *)invocation timeInterval:(NSTimeInterval)timeInterval willRepeat:(BOOL)willRepeat
{
return [NSTimer timerWithTimeInterval:timeInterval invocation:invocation repeats:willRepeat];
}
- (NSInvocation*)getInvocation:(SEL)methodName arguments:(NSMutableArray*)arguments
{
NSMethodSignature *sig = [self methodSignatureForSelector:methodName];
NSInvocation *invocation = [NSInvocation invocationWithMethodSignature:sig];
[invocation setTarget:self];
[invocation setSelector:methodName];
if (arguments != nil)
{
id arg1 = [arguments objectAtIndex:0];
id arg2 = [arguments objectAtIndex:1];
[invocation setArgument:&arg1 atIndex:2];
[invocation setArgument:&arg2 atIndex:3];
}
return invocation;
}
- (void)addTimerToRunLoop:(NSTimer*)timer
{
[[NSRunLoop mainRunLoop] addTimer:timer forMode:NSDefaultRunLoopMode];
}