快速旋转无刻度的人像

Question

我遇到swift的问题，我有一个应用程序，当按下按钮时，必须旋转90°的图像，为此我使用此代码

extension UIImage {
public func imageRotatedByDegrees(degrees: CGFloat, flip: Bool) -> UIImage {
    let radiansToDegrees: (CGFloat) -> CGFloat = {
        return $0 * (180.0 / CGFloat(M_PI))
    }
    let degreesToRadians: (CGFloat) -> CGFloat = {
        return $0 / 180.0 * CGFloat(M_PI)
    }

    // calculate the size of the rotated view's containing box for our drawing space
    let rotatedViewBox = UIView(frame: CGRect(origin: CGPointZero, size: size))
    let t = CGAffineTransformMakeRotation(degreesToRadians(degrees));
    rotatedViewBox.transform = t
    let rotatedSize = rotatedViewBox.frame.size

    // Create the bitmap context
    UIGraphicsBeginImageContext(rotatedSize)
    let bitmap = UIGraphicsGetCurrentContext()

    // Move the origin to the middle of the image so we will rotate and scale around the center.
    CGContextTranslateCTM(bitmap, 0.5 * rotatedSize.width, 0.5 * rotatedSize.height);

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

    // Now, draw the rotated/scaled image into the context
    var yFlip: CGFloat

    if(flip){
        yFlip = CGFloat(-1.0)
    } else {
        yFlip = CGFloat(1.0)
    }

    CGContextScaleCTM(bitmap, yFlip, -1.0)
    CGContextDrawImage(bitmap, CGRectMake(-size.width / 2, -size.height / 2, size.width, size.height), CGImage)

    let newImage = UIGraphicsGetImageFromCurrentImageContext()
    UIGraphicsEndImageContext()

    return newImage
}}

在风景图片中我没有任何问题但是当我尝试以纵向旋转图像时，在第一次按下按钮时，图像会缩放，使其宽度适应ImageView的宽度，丢失其比例，以及没有旋转，它会旋转，总是以新的比例旋转，只有第二次压力......任何人都可以帮助我吗？

这里是起始情况的截图

首次按下后

第二次按

后