返回所需要修改尺寸的图片

-(UIImage*) OriginImage:(UIImage *)image scaleToSize:(CGSize)size

{

UIGraphicsBeginImageContext(size); //size 为CGSize类型，即你所需要的图片尺寸

[image drawInRect:CGRectMake(0, 0, size.width, size.height)];

UIImage* scaledImage = UIGraphicsGetImageFromCurrentImageContext();

UIGraphicsEndImageContext();

return scaledImage; //返回的就是已经改变的图片

}