转自：http://www.oschina.net/code/snippet_2248391_53038
//
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; } }}