// 获取图片的size        CGSize size = [UIImage imageNamed:@"regStep2_sex"].size;

// 根据图片url获取图片尺寸+(CGSize)getImageSizeWithURL:(id)imageURL{    NSURL* URL = nil;    if([imageURL isKindOfClass:[NSURL class]]){        URL = imageURL;    }    if([imageURL isKindOfClass:[NSString class]]){        URL = [NSURL URLWithString:imageURL];    }    if(URL == nil)        return CGSizeZero;                  // url不正确返回CGSizeZero         NSMutableURLRequest *request = [[NSMutableURLRequest alloc] initWithURL:URL];    NSString* pathExtendsion = [URL.pathExtension lowercaseString];         CGSize size = CGSizeZero;    if([pathExtendsion isEqualToString:@"png"]){        size =  [self getPNGImageSizeWithRequest:request];    }    else if([pathExtendsion isEqual:@"gif"])    {        size =  [self getGIFImageSizeWithRequest:request];    }    else{        size = [self getJPGImageSizeWithRequest:request];    }    if(CGSizeEqualToSize(CGSizeZero, size))                    // 如果获取文件头信息失败,发送异步请求请求原图    {        NSData* data =http://www.mamicode.com/ [NSURLConnection sendSynchronousRequest:[NSURLRequest requestWithURL:URL] returningResponse:nil error:nil];        UIImage* image = [UIImage imageWithData:data];        if(image)        {            size = image.size;        }    }    return size;}//  获取PNG图片的大小+(CGSize)getPNGImageSizeWithRequest:(NSMutableURLRequest*)request{    [request setValue:@"bytes=16-23" forHTTPHeaderField:@"Range"];    NSData* data =http://www.mamicode.com/ [NSURLConnection sendSynchronousRequest:request returningResponse:nil error:nil];    if(data.length == 8)    {        int w1 = 0, w2 = 0, w3 = 0, w4 = 0;        [data getBytes:&w1 range:NSMakeRange(0, 1)];        [data getBytes:&w2 range:NSMakeRange(1, 1)];        [data getBytes:&w3 range:NSMakeRange(2, 1)];        [data getBytes:&w4 range:NSMakeRange(3, 1)];        int w = (w1 << 24) + (w2 << 16) + (w3 << 8) + w4;        int h1 = 0, h2 = 0, h3 = 0, h4 = 0;        [data getBytes:&h1 range:NSMakeRange(4, 1)];        [data getBytes:&h2 range:NSMakeRange(5, 1)];        [data getBytes:&h3 range:NSMakeRange(6, 1)];        [data getBytes:&h4 range:NSMakeRange(7, 1)];        int h = (h1 << 24) + (h2 << 16) + (h3 << 8) + h4;        return CGSizeMake(w, h);    }    return CGSizeZero;}//  获取gif图片的大小+(CGSize)getGIFImageSizeWithRequest:(NSMutableURLRequest*)request{    [request setValue:@"bytes=6-9" forHTTPHeaderField:@"Range"];    NSData* data =http://www.mamicode.com/ [NSURLConnection sendSynchronousRequest:request returningResponse:nil error:nil];    if(data.length == 4)    {        short w1 = 0, w2 = 0;        [data getBytes:&w1 range:NSMakeRange(0, 1)];        [data getBytes:&w2 range:NSMakeRange(1, 1)];        short w = w1 + (w2 << 8);        short h1 = 0, h2 = 0;        [data getBytes:&h1 range:NSMakeRange(2, 1)];        [data getBytes:&h2 range:NSMakeRange(3, 1)];        short h = h1 + (h2 << 8);        return CGSizeMake(w, h);    }    return CGSizeZero;}//  获取jpg图片的大小+(CGSize)getJPGImageSizeWithRequest:(NSMutableURLRequest*)request{    [request setValue:@"bytes=0-209" forHTTPHeaderField:@"Range"];    NSData* data =http://www.mamicode.com/ [NSURLConnection sendSynchronousRequest:request returningResponse:nil error:nil];         if ([data length] <= 0x58) {        return CGSizeZero;    }         if ([data length] < 210) {// 肯定只有一个DQT字段        short w1 = 0, w2 = 0;        [data getBytes:&w1 range:NSMakeRange(0x60, 0x1)];        [data getBytes:&w2 range:NSMakeRange(0x61, 0x1)];        short w = (w1 << 8) + w2;        short h1 = 0, h2 = 0;        [data getBytes:&h1 range:NSMakeRange(0x5e, 0x1)];        [data getBytes:&h2 range:NSMakeRange(0x5f, 0x1)];        short h = (h1 << 8) + h2;        return CGSizeMake(w, h);    } else {        short word = 0x0;        [data getBytes:&word range:NSMakeRange(0x15, 0x1)];        if (word == 0xdb) {            [data getBytes:&word range:NSMakeRange(0x5a, 0x1)];            if (word == 0xdb) {// 两个DQT字段                short w1 = 0, w2 = 0;                [data getBytes:&w1 range:NSMakeRange(0xa5, 0x1)];                [data getBytes:&w2 range:NSMakeRange(0xa6, 0x1)];                short w = (w1 << 8) + w2;                short h1 = 0, h2 = 0;                [data getBytes:&h1 range:NSMakeRange(0xa3, 0x1)];                [data getBytes:&h2 range:NSMakeRange(0xa4, 0x1)];                short h = (h1 << 8) + h2;                return CGSizeMake(w, h);            } else {// 一个DQT字段                short w1 = 0, w2 = 0;                [data getBytes:&w1 range:NSMakeRange(0x60, 0x1)];                [data getBytes:&w2 range:NSMakeRange(0x61, 0x1)];                short w = (w1 << 8) + w2;                short h1 = 0, h2 = 0;                [data getBytes:&h1 range:NSMakeRange(0x5e, 0x1)];                [data getBytes:&h2 range:NSMakeRange(0x5f, 0x1)];                short h = (h1 << 8) + h2;                return CGSizeMake(w, h);            }        } else {            return CGSizeZero;        }    }}