http://www.cnblogs.com/zhangdadi/archive/2012/11/17/2774919.html

http://bbs.csdn.net/topics/390898581

ios 改变图片大小缩放方法

-(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
}