我正在使用iOS 7应用程序,并希望动画更改UILabel的内容.我不想做任何图形动画,如淡化旧内容/淡入新内容.因此,iOS提供的所有标准动画功能(如图层动画或动画块)无法使用(至少我认为).
假设UILabel显示“200 V”的仪表值,此文本应更改为“400 V”.文本不应该只是从“200 V”跳到“400 V”,而应该使用一些缓动功能计数：“200 V”,“220 V”,“240 V”…“390 V”,“395 V“…”400 V“
在Android中可以使用ValueAnimator轻松解决：
ValueAnimator animation = ValueAnimator.ofFloat(0f,1f);
animation.setInterpolation(new EaSEOutInterpolator());
animation.setDuration(2500);
animation.setStartDelay(500);
animation.addUpdateListener(new AnimatorUpdateListener() {
@Override
public void onAnimationUpate(ValueAnimator animator) {
float currentValue = animator.getAnimatedValue.floatValue();
label1.setText(String.format("%.2",fromValue1 + ((tovalue1 - fromValue1) * currentValue)));
label2.setText(String.format("%.2",fromValue2 + ((tovalue2 - fromValue2) * currentValue)));
...
}
});
animation.start();
iOS还有这样的事情吗？我发现不同的解决方案,但它们都很旧(2010/11),并且最终都使用NSTimer和自己的缓动功能手动实现这个行为.
没有问题,可以自己实现这一点,但这将是相当麻烦,不是非常优雅.那么在iOS中有没有什么可以解决这个问题呢,还是至少有方便的第三方实现？
非常感谢你！
解决方法
因为我没有找到定制的解决方案,我创建了我自己的：一个简单的动画师类,处理轻松：
// MyValueAnimation.h
typedef void (^MyAnimationBlock)(double animationValue);
@interface MyValueAnimation : NSObject
- (void)startAnimation:(MyAnimationBlock)animationBlock runtime:(NSUInteger)runtime delay:(NSUInteger)delay;
@end
// MyValueAnimation.m
#import "MyValueAnimation.h"
// Number of seconds between each animation step
#define kStepSize 0.05
@interface MyValueAnimation () {
NSTimer *timer;
NSUInteger totalRunTime; // Total duration of the animation (delay not included)
NSUInteger currentRuntime; // Time the animation is already running
MyAnimationBlock animationBlock;
}
@end
@implementation MyValueAnimation
- (void)startAnimation:(MyAnimationBlock)block runtime:(NSUInteger)runtime delay:(NSUInteger)delay {
if (timer != nil)
[timer invalidate];
timer = nil;
totalRunTime = runtime;
animationBlock = block;
currentRuntime = 0;
if (block != nil) {
if (delay > 0) {
// Wait to delay the start. Convert delay from millis to seconds
double delaySeconds = (double)delay / 1000.0;
timer = [NSTimer scheduledTimerWithTimeInterval:delaySeconds target:self selector:@selector(delayTick:) userInfo:nil repeats:false];
} else {
// Run the animation
timer = [NSTimer scheduledTimerWithTimeInterval:kStepSize target:self selector:@selector(animationTick:) userInfo:nil repeats:true];
}
}
}
- (void)delayTick:(NSTimer *)delayTimer {
// End of delay -> run animation
[delayTimer invalidate];
timer = [NSTimer scheduledTimerWithTimeInterval:kStepSize target:self selector:@selector(animationTick:) userInfo:nil repeats:true];
}
- (void)animationTick:(NSTimer *)animationTimer {
NSUInteger step = 1000 * kStepSize; // step size/length in milli seconds
currentRuntime += step;
double progress = MIN((double)currentRuntime / (double)totalRunTime,1.0);
// Progress is a value between 0 and 1. The easing function maps this
// to the animationValue which is than used inside the animationBlock
// to calculate the current value of the animiation
double animationValue = [self customEaSEOut:progress];
if (animationBlock != nil)
animationBlock(animationValue);
if (progress >= 1.0) {
// Animation complete
[timer invalidate];
timer = nil;
}
}
- (double)customEaSEOut:(double)t {
// Use any easing function you like to animate your values...
// http://rechneronline.de/function-graphs/
// http://sol.gfxile.net/interpolation/
return (1 - pow(1-t,2));
}
@end
// =============================================================
// Some code using the animation
- (void)animateValueFrom:(double)fromValue to:(double)tovalue {
if (valueAnimation == nil)
valueAnimation = [[MyValueAnimation alloc] init];
MyAnimationBlock animationBlock = ^(double animationValue) {
double currentValue = fromValue + ((tovalue - fromValue) * animationValue);
someLabel.text = [Nsstring stringWithFormat:"%dV",currentValue];
};
[valueAnimation startAnimation:animationBlock runtime:1500 delay:500];
}
也许不是最漂亮的解决方案,但它的作品:-)