iOS等比例缩放图片方法

-(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
}