压缩图片100k以内

-(NSData *)imageData:(UIImage *)myimage
    {
        NSData *data=UIImageJPEGRepresentation(myimage,       1.0);
        if (data.length>100*1024) {
            if (data.length>2*1024*1024) {//2M以及以上
                data=UIImageJPEGRepresentation(myimage, 0.1);
            }else if (data.length>512*1024) {//0.5M-2M
                data=UIImageJPEGRepresentation(myimage, 0.5);
            }else if (data.length>200*1024) {//0.25M-0.5M
                data=UIImageJPEGRepresentation(myimage, 0.9);
            }
        }
        return data;
    }