我试图旋转一个UIImageView 360度，并在网上看了几个教程。我不能让它们都工作，UIView要么停止，要么跳转到一个新位置。
我怎样才能做到这一点呢?
我最近尝试的是:
[UIView animateWithDuration:1.0
delay:0.0
options:0
animations:^{
imageToMove.transform = CGAffineTransformMakeRotation(M_PI);
}
completion:^(BOOL finished){
NSLog(@"Done!");
}];
但如果我使用2*pi，它根本不会移动(因为它是相同的位置)。如果我尝试只做(180度)，它可以工作，但如果我再次调用这个方法，它会向后旋转。
编辑:
[UIView animateWithDuration:1.0
delay:0.0
options:0
animations:^{
[UIView setAnimationRepeatCount:HUGE_VALF];
[UIView setAnimationBeginsFromCurrentState:YES];
imageToMove.transform = CGAffineTransformMakeRotation(M_PI);
}
completion:^(BOOL finished){
NSLog(@"Done!");
}];
也不管用。它会转到180度，暂停一秒钟，然后在重新开始之前重置回0度。
Nate上面的答案是理想的停止和开始动画，并提供了一个更好的控制。我很好奇为什么你的没用，而他的有用。我想在这里分享我的发现和一个更简单的代码版本，它可以使UIView连续动画而不停顿。
这是我用的代码，
- (void)rotateImageView
{
[UIView animateWithDuration:1 delay:0 options:UIViewAnimationOptionCurveLinear animations:^{
[self.imageView setTransform:CGAffineTransformRotate(self.imageView.transform, M_PI_2)];
}completion:^(BOOL finished){
if (finished) {
[self rotateImageView];
}
}];
}
我使用“CGAffineTransformRotate”而不是“CGAffineTransformMakeRotation”，因为前者返回的结果是随着动画的进行而保存的。这将防止在动画期间视图的跳跃或重置。
另一件事是不要使用'UIViewAnimationOptionRepeat'因为在动画的结尾，在它开始重复之前，它会重置变换，使视图跳回它的原始位置。不是重复，而是递归，这样转换就永远不会重置为原始值，因为动画块实际上永远不会结束。
最后一件事是，你必须以90度(M_PI / 2)的步伐转换视图，而不是360度或180度(2*M_PI或M_PI)。因为变换是正弦和余弦值的矩阵乘法。
t' = [ cos(angle) sin(angle) -sin(angle) cos(angle) 0 0 ] * t
所以，假设你使用180度变换，cos(180)产生-1，使得视图每次都在相反的方向变换(如果你把变换的弧度值改为M_PI, Note-Nate的答案也会有这个问题)。360度转换只是要求视图保持在原来的位置，因此你根本看不到任何旋转。
我在这个库中找到了很好的代码，
下面是它的代码，我做了一些小的改变，根据我的速度需要:)
UIImageView + Rotate.h
#import <Foundation/Foundation.h>
@interface UIImageView (Rotate)
- (void)rotate360WithDuration:(CGFloat)duration repeatCount:(float)repeatCount;
- (void)pauseAnimations;
- (void)resumeAnimations;
- (void)stopAllAnimations;
@end
UIImageView + Rotate.m
#import <QuartzCore/QuartzCore.h>
#import "UIImageView+Rotate.h"
@implementation UIImageView (Rotate)
- (void)rotate360WithDuration:(CGFloat)duration repeatCount:(float)repeatCount
{
CABasicAnimation *fullRotation;
fullRotation = [CABasicAnimation animationWithKeyPath:@"transform.rotation"];
fullRotation.fromValue = [NSNumber numberWithFloat:0];
//fullRotation.toValue = [NSNumber numberWithFloat:(2*M_PI)];
fullRotation.toValue = [NSNumber numberWithFloat:-(2*M_PI)]; // added this minus sign as i want to rotate it to anticlockwise
fullRotation.duration = duration;
fullRotation.speed = 2.0f; // Changed rotation speed
if (repeatCount == 0)
fullRotation.repeatCount = MAXFLOAT;
else
fullRotation.repeatCount = repeatCount;
[self.layer addAnimation:fullRotation forKey:@"360"];
}
//Not using this methods :)
- (void)stopAllAnimations
{
[self.layer removeAllAnimations];
};
- (void)pauseAnimations
{
[self pauseLayer:self.layer];
}
- (void)resumeAnimations
{
[self resumeLayer:self.layer];
}
- (void)pauseLayer:(CALayer *)layer
{
CFTimeInterval pausedTime = [layer convertTime:CACurrentMediaTime() fromLayer:nil];
layer.speed = 0.0;
layer.timeOffset = pausedTime;
}
- (void)resumeLayer:(CALayer *)layer
{
CFTimeInterval pausedTime = [layer timeOffset];
layer.speed = 1.0;
layer.timeOffset = 0.0;
layer.beginTime = 0.0;
CFTimeInterval timeSincePause = [layer convertTime:CACurrentMediaTime() fromLayer:nil] - pausedTime;
layer.beginTime = timeSincePause;
}
@end
Swift 5使用关键帧动画的UIView扩展
这个方法允许我们直接使用UIView.AnimationOptions.repeat
public extension UIView {
func animateRotation(duration: TimeInterval, repeat: Bool, completion: ((Bool) -> ())?) {
var options = UIView.KeyframeAnimationOptions(rawValue: UIView.AnimationOptions.curveLinear.rawValue)
if `repeat` {
options.insert(.repeat)
}
UIView.animateKeyframes(withDuration: duration, delay: 0, options: options, animations: {
UIView.addKeyframe(withRelativeStartTime: 0, relativeDuration: 0.25, animations: {
self.transform = CGAffineTransform(rotationAngle: CGFloat.pi/2)
})
UIView.addKeyframe(withRelativeStartTime: 0.25, relativeDuration: 0.25, animations: {
self.transform = CGAffineTransform(rotationAngle: CGFloat.pi)
})
UIView.addKeyframe(withRelativeStartTime: 0.5, relativeDuration: 0.25, animations: {
self.transform = CGAffineTransform(rotationAngle: 3*CGFloat.pi/2)
})
UIView.addKeyframe(withRelativeStartTime: 0.75, relativeDuration: 0.25, animations: {
self.transform = CGAffineTransform(rotationAngle: 2*CGFloat.pi)
})
}, completion: completion)
}
}
创建动画
- (CABasicAnimation *)spinAnimationWithDuration:(CGFloat)duration clockwise:(BOOL)clockwise repeat:(BOOL)repeats
{
CABasicAnimation *anim = [CABasicAnimation animationWithKeyPath:@"transform.rotation.z"];
anim.toValue = clockwise ? @(M_PI * 2.0) : @(M_PI * -2.0);
anim.duration = duration;
anim.cumulative = YES;
anim.repeatCount = repeats ? CGFLOAT_MAX : 0;
return anim;
}
将它添加到这样的视图中
CABasicAnimation *animation = [self spinAnimationWithDuration:1.0 clockwise:YES repeat:YES];
[self.spinningView.layer addAnimation:animation forKey:@"rotationAnimation"];
这个答案有什么不同?如果你的大部分函数都返回对象，而不是在这里和那里操作一些对象，你会有更干净的代码。
