IOS 视图缩放

- (UIImage *)scaleImage:(UIImage *)image toScale:(CGSize )scaleSize
{
    UIGraphicsBeginImageContext(scaleSize);
    [image drawInRect:CGRectMake(0, 0, scaleSize.width, scaleSize.height)];
    UIImage *scaledImage = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    return scaledImage;
}