Question

我需要轮换UIImageView或UIImage中的UIImageView，同时使用NSTimer移动其框架。这是NSTimer运动：

timer = [NSTimer scheduledTimerWithTimeInterval:time target:self selector:@selector(animate) userInfo:nil repeats:YES];

这是动画方法（它的一部分，最重要的）：

CGRect viewLocation = [[[self layer] presentationLayer] frame];
                self.frame = CGRectMake(viewLocation.origin.x, viewLocation.origin.y + 0.2, viewLocation.size.width, viewLocation.size.height);

这是我试图用来旋转UIImage的方法：

- (UIImage *)imageRotatedByDegrees:(CGFloat)degrees
{
    // calculate the size of the rotated view's containing box for our drawing space
    UIView *rotatedViewBox = [[UIView alloc] initWithFrame:CGRectMake(0,0,self.size.width, self.size.height)];
    CGAffineTransform t = CGAffineTransformMakeRotation(DegreesToRadians(degrees));
    rotatedViewBox.transform = t;
    CGSize rotatedSize = rotatedViewBox.frame.size;
    [rotatedViewBox release];

    // Create the bitmap context
    UIGraphicsBeginImageContext(rotatedSize);
    CGContextRef bitmap = UIGraphicsGetCurrentContext();

    // Move the origin to the middle of the image so we will rotate and scale around the center.
    CGContextTranslateCTM(bitmap, rotatedSize.width/2, rotatedSize.height/2);

    // Rotate the image context
    CGContextRotateCTM(bitmap, DegreesToRadians(degrees));

    // Now, draw the rotated/scaled image into the context
    CGContextScaleCTM(bitmap, 1.0, -1.0);
    CGContextDrawImage(bitmap, CGRectMake(-self.size.width / 2, -self.size.height / 2, self.size.width, self.size.height), [self CGImage]);

    UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    return newImage;
}

此代码位于UIImageView的子类中，因此self被称为UIImageView。

我还尝试使用CGAffineTransform旋转UIImageView，但UIImageView正在被拉伸并以奇怪的方式旋转。这是方法：

- (void)rotateWithDegrees:(CGFloat)degrees {
    CGAffineTransform transform = CGAffineTransformMakeRotation(DEGREES_TO_RADIANS(degrees));
    self.transform = transform;
}

这是宏：

#define DEGREES_TO_RADIANS(angle) (angle / 180.0 * M_PI)

重要的是你总是可以使用计时器来移动对象，这样那部分是不可更改的。

Answer 1

我找到了解决方案！首先，我们排除提供UIImage调整大小的解决方案。所以，我们旋转UIImageView，但是当使用CGAffineTransform时，框架不能被修改！因此，要使用计时器移动UIImageView，我们必须修改UIImageView的中心。这是删除：

CGRect viewLocation = [[[self layer] presentationLayer] frame];
self.frame = CGRectMake(viewLocation.origin.x, viewLocation.origin.y + 0.2, viewLocation.size.width, viewLocation.size.height);

这是补充：

self.center = CGPointMake(self.frame.origin.x + (self.frame.size.width / 2), self.frame.origin.y + 0.2 + (self.frame.size.height / 2));

然后，我们可以使用rotateWithDegrees:方法来轮播UIImageView：

- (void)rotateWithDegrees:(CGFloat)degrees {
    CGAffineTransform transform = CGAffineTransformMakeRotation(DEGREES_TO_RADIANS(degrees));
    self.transform = transform;
    _degrees+=0.5;
    if (_degrees == 360) {
        _degrees = 1;
    }
}

所以，我们可以添加一行：

[self rotateWithDegrees:_degrees];

下面：

self.center = CGPointMake(self.frame.origin.x + (self.frame.size.width / 2), self.frame.origin.y + 0.2 + (self.frame.size.height / 2));

UIImageView由于其中心的变化而移动，而不是由于其框架的更改而允许使用CGAffineTransform进行旋转。

iOS - 使用NSTimer移动框架时旋转UIImageView或UIImage

1 个答案: