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

霉霉4更新了David Rysanek的精彩回答:

import UIKit

extension UIView {

        func startRotating(duration: CFTimeInterval = 3, repeatCount: Float = Float.infinity, clockwise: Bool = true) {

            if self.layer.animation(forKey: "transform.rotation.z") != nil {
                return
            }

            let animation = CABasicAnimation(keyPath: "transform.rotation.z")
            let direction = clockwise ? 1.0 : -1.0
            animation.toValue = NSNumber(value: .pi * 2 * direction)
            animation.duration = duration
            animation.isCumulative = true
            animation.repeatCount = repeatCount
            self.layer.add(animation, forKey:"transform.rotation.z")
        }

        func stopRotating() {

            self.layer.removeAnimation(forKey: "transform.rotation.z")

        }   

    }
}

其他回答

我发现了一个非常适合我的方法(我稍微修改了一下):iphone UIImageView旋转

#import <QuartzCore/QuartzCore.h>

- (void) runSpinAnimationOnView:(UIView*)view duration:(CGFloat)duration rotations:(CGFloat)rotations repeat:(float)repeat {
    CABasicAnimation* rotationAnimation;
    rotationAnimation = [CABasicAnimation animationWithKeyPath:@"transform.rotation.z"];
    rotationAnimation.toValue = [NSNumber numberWithFloat: M_PI * 2.0 /* full rotation*/ * rotations * duration ];
    rotationAnimation.duration = duration;
    rotationAnimation.cumulative = YES;
    rotationAnimation.repeatCount = repeat ? HUGE_VALF : 0;

    [view.layer addAnimation:rotationAnimation forKey:@"rotationAnimation"];
}

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();

Swift3版本:

extension UIView {

    func startRotate() {
        let rotation : CABasicAnimation = CABasicAnimation(keyPath: "transform.rotation.z")
        rotation.fromValue = 0
        rotation.toValue = NSNumber(value: M_PI * 2)
        rotation.duration = 2
        rotation.isCumulative = true
        rotation.repeatCount = FLT_MAX
        self.layer.add(rotation, forKey: "rotationAnimation")
    }

    func stopRotate() {
        self.layer.removeAnimation(forKey: "rotationAnimation")
    }
}

记住在viewWillAppear中调用startRotate,而不是在viewDidLoad中。

迅速:

func runSpinAnimationOnView(view:UIView , duration:Float, rotations:Double, repeatt:Float ) ->()
    {
        let rotationAnimation=CABasicAnimation();

        rotationAnimation.keyPath="transform.rotation.z"

        let toValue = M_PI * 2.0 * rotations ;


        // passing it a float
        let someInterval = CFTimeInterval(duration)

        rotationAnimation.toValue=toValue;
        rotationAnimation.duration=someInterval;
        rotationAnimation.cumulative=true;
        rotationAnimation.repeatCount=repeatt;
        view.layer.addAnimation(rotationAnimation, forKey: "rotationAnimation")


    }

这对我很管用:

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