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。


当前回答

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

其他回答

let val = CGFloat(M_PI_2)

UIView.animate(withDuration: 1, delay: 0, options: [.repeat, .curveLinear], animations: {
        self.viewToRotate.transform = self.viewToRotate.transform.rotated(by: val)
})

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();

使用四分之一转弯,并逐步增加转弯。

void (^block)() = ^{
    imageToMove.transform = CGAffineTransformRotate(imageToMove.transform, M_PI / 2);
}

void (^completion)(BOOL) = ^(BOOL finished){
    [UIView animateWithDuration:1.0
                          delay:0.0
                        options:0
                     animations:block
                     completion:completion];
}

completion(YES);

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。

这对我很管用:

[UIView animateWithDuration:1.0
                animations:^
{
    self.imageView.transform = CGAffineTransformMakeRotation(M_PI);
    self.imageView.transform = CGAffineTransformMakeRotation(0);
}];