Xcode 图像旋转 toValue 和 fromValue

Xcode image rotation toValue and fromValue

提问by Maurice

I want to turn an image 190 degrees when pressing a button. That works but when i press the button again the animation needs to start where it last ended, instead of starting from 0. So everytime i press the button, the animation need to turn a 190 degrees.

我想在按下按钮时将图像旋转 190 度。这有效，但是当我再次按下按钮时，动画需要从上次结束的位置开始，而不是从 0 开始。所以每次我按下按钮时，动画都需要旋转 190 度。

It is starting at 0 everytime becouse my fromValue is set to 0.

每次都从 0 开始，因为我的 fromValue 设置为 0。

Does someone know how i can make the fromValue start where my image ends. My code is below here.

有人知道我如何让 fromValue 从我的图像结束的地方开始。我的代码在下面。

- (IBAction)buttonPressed
{ 
    CABasicAnimation *imageRotation = [CABasicAnimation animationWithKeyPath:@"transform.rotation"];

    imageRotation.fromValue = [NSNumber numberWithFloat:0];
    imageRotation.toValue = [NSNumber numberWithFloat:((190*M_PI)/ -180)];

    imageRotation.duration = 1.5;
    imageRotation.repeatCount = 1;

    imageRotation.removedOnCompletion = NO;
    imageRotation.autoreverses=NO;
    imageRotation.fillMode = kCAFillModeForwards;

    [image.layer addAnimation:imageRotation forKey:@"imageRotation"];
}

回答by Maurice

Thanks for your answer, but here is how i did it. Hope people can use this :D

感谢您的回答，但我是这样做的。希望人们可以使用这个：D

My .h file looks like this:

我的 .h 文件如下所示：

#import <UIKit/UIKit.h>
#import <QuartzCore/QuartzCore.h>

@interface testViewController : UIViewController {
   IBOutlet UIImageView *image;
   NSObject *lastValue;
}

- (IBAction)buttonPressed;

@property(nonatomic, retain) IBOutlet NSObject *lastValue;

@end

My .m file looks like this:

我的 .m 文件如下所示：

@synthesize lastValue;

- (void)viewAnimation0 
{
   CABasicAnimation *imageRotation = [CABasicAnimation animationWithKeyPath:@"transform.rotation"];

   imageRotation.fromValue = lastValue;
   imageRotation.toValue = [NSNumber numberWithFloat:((30*M_PI)/ -180)];
   lastValue = imageRotation.toValue;

   imageRotation.duration = 1.5;
   imageRotation.repeatCount = 1;

   imageRotation.removedOnCompletion = NO;
   imageRotation.autoreverses=NO;
   imageRotation.fillMode = kCAFillModeForwards;

   [image.layer addAnimation:imageRotation forKey:@"imageRotation"];
}

- (void)viewAnimation1 
{
   CABasicAnimation *imageRotation = [CABasicAnimation animationWithKeyPath:@"transform.rotation"];

   imageRotation.fromValue = lastValue;
   imageRotation.toValue = [NSNumber numberWithFloat:((60*M_PI)/ -180)];
   lastValue = imageRotation.toValue;

   imageRotation.duration = 1.5;
   imageRotation.repeatCount = 1;

   imageRotation.removedOnCompletion = NO;
   imageRotation.autoreverses=NO;
   imageRotation.fillMode = kCAFillModeForwards;

   [image.layer addAnimation:imageRotation forKey:@"imageRotation"];
}

- (void)viewAnimation2 
{
   CABasicAnimation *imageRotation = [CABasicAnimation animationWithKeyPath:@"transform.rotation"];

   imageRotation.fromValue = lastValue;
   imageRotation.toValue = [NSNumber numberWithFloat:((90*M_PI)/ -180)];
   lastValue = imageRotation.toValue;

   imageRotation.duration = 1.5;
   imageRotation.repeatCount = 1;

   imageRotation.removedOnCompletion = NO;
   imageRotation.autoreverses=NO;
   imageRotation.fillMode = kCAFillModeForwards;

   [image.layer addAnimation:imageRotation forKey:@"imageRotation"];
}

- (IBAction)buttonPressed 
{
   static int counter = 0;
   switch (++counter) {

    case 1:
        [self viewAnimation1];
        break;

    case 2:
        [self viewAnimation2];
        break;

    default:
        [self viewAnimation0];
        counter = 0;
        break;
   }
   //    animateButton.enabled = NO;
} 

回答by rob mayoff

You need to do two things: you need to actually set the rotation of the layer (instead of setting removedOnCompletion = NO), and you need to not set the fromValue.

您需要做两件事：您需要实际设置图层的旋转（而不是设置removedOnCompletion = NO），并且您不需要设置fromValue.

- (IBAction)buttonPressed
{
    CABasicAnimation *imageRotation = [CABasicAnimation animationWithKeyPath:@"transform.rotation"];

    imageRotation.toValue = [NSNumber numberWithFloat:((190*M_PI)/ -180)];

    imageRotation.duration = 1.5;
    imageRotation.repeatCount = 1;

    [image.layer setValue:imageRotation.toValue forKey:imageRotation.keyPath];
    [image.layer addAnimation:imageRotation forKey:@"imageRotation"];
}

Watch the Core Animation Essentialsvideo from WWDC 2011to understand why you need to set the layer's property instead of setting removedOnCompletion = NO.

观看WWDC 2011的Core Animation Essentials视频，了解为什么需要设置图层的属性而不是设置.removedOnCompletion = NO