IOS 获取图片的size

// 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 = [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 = [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 = [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 = [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;    }}

}