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。
如果你想要做的只是无休止地旋转图像，这很好，而且非常简单:
NSTimeInterval duration = 10.0f;
CGFloat angle = M_PI / 2.0f;
CGAffineTransform rotateTransform = CGAffineTransformRotate(imageView.transform, angle);
[UIView animateWithDuration:duration delay:0 options:UIViewAnimationOptionRepeat| UIViewAnimationOptionCurveLinear animations:^{
imageView.transform = rotateTransform;
} completion:nil];
根据我的经验，这是完美的，但要确保你的图像能够在没有任何偏移的情况下围绕其中心旋转，否则图像动画将“跳跃”一旦它到达PI。
要改变旋转的方向，改变角度的符号(angle *= -1)。
@AlexPretzlav的更新评论让我重新审视了这个问题，我意识到当我写这篇文章时，我旋转的图像是沿着垂直和水平轴镜像的，这意味着图像确实只旋转了90度，然后重置，尽管它看起来像在继续旋转。
所以，如果你的图像像我的一样，这将工作得很好，然而，如果图像不是对称的，你会注意到90度后“snap”回到原来的方向。
要旋转非对称图像，最好使用公认的答案。
这些不太优雅的解决方案之一，如下所示，将真正旋转图像，但当动画重新启动时可能会有明显的口吃:
- (void)spin
{
NSTimeInterval duration = 0.5f;
CGFloat angle = M_PI_2;
CGAffineTransform rotateTransform = CGAffineTransformRotate(self.imageView.transform, angle);
[UIView animateWithDuration:duration delay:0 options:UIViewAnimationOptionCurveLinear animations:^{
self.imageView.transform = rotateTransform;
} completion:^(BOOL finished) {
[self spin];
}];
}
你也可以像@richard-j-ross-iii建议的那样只用块来做，但你会得到一个保留循环警告，因为块正在捕获自己:
__block void(^spin)() = ^{
NSTimeInterval duration = 0.5f;
CGFloat angle = M_PI_2;
CGAffineTransform rotateTransform = CGAffineTransformRotate(self.imageView.transform, angle);
[UIView animateWithDuration:duration delay:0 options:UIViewAnimationOptionCurveLinear animations:^{
self.imageView.transform = rotateTransform;
} completion:^(BOOL finished) {
spin();
}];
};
spin();
@ram的回答很有帮助。以下是Swift版本的答案。
斯威夫特2
private func rotateImageView() {
UIView.animateWithDuration(1, delay: 0, options: UIViewAnimationOptions.CurveLinear, animations: { () -> Void in
self.imageView.transform = CGAffineTransformRotate(self.imageView.transform, CGFloat(M_PI_2))
}) { (finished) -> Void in
if finished {
self.rotateImageView()
}
}
}
斯威夫特3、4、5所示
private func rotateImageView() {
UIView.animate(withDuration: 1, delay: 0, options: UIView.AnimationOptions.curveLinear, animations: { () -> Void in
self.imageView.transform = self.imageView.transform.rotated(by: .pi / 2)
}) { (finished) -> Void in
if finished {
self.rotateImageView()
}
}
}
使用UIView执行360度动画有以下几种不同的方法。
使用CABasicAnimation
var rotationAnimation = CABasicAnimation()
rotationAnimation = CABasicAnimation.init(keyPath: "transform.rotation.z")
rotationAnimation.toValue = NSNumber(value: (Double.pi))
rotationAnimation.duration = 1.0
rotationAnimation.isCumulative = true
rotationAnimation.repeatCount = 100.0
view.layer.add(rotationAnimation, forKey: "rotationAnimation")
下面是UIView的一个扩展函数，它处理启动和停止旋转操作:
extension UIView {
// Start rotation
func startRotation() {
let rotation = CABasicAnimation(keyPath: "transform.rotation.z")
rotation.fromValue = 0
rotation.toValue = NSNumber(value: Double.pi)
rotation.duration = 1.0
rotation.isCumulative = true
rotation.repeatCount = FLT_MAX
self.layer.add(rotation, forKey: "rotationAnimation")
}
// Stop rotation
func stopRotation() {
self.layer.removeAnimation(forKey: "rotationAnimation")
}
}
现在使用UIView。动画关闭:
UIView.animate(withDuration: 0.5, animations: {
view.transform = CGAffineTransform(rotationAngle: (CGFloat(Double.pi))
}) { (isAnimationComplete) in
// Animation completed
}
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
