可以在UIImage的分类中加入下面的代码,并且引入系统的ImageIO.framework
/** 根据图片的url获取尺寸 @param URL url @return CGSize */ + (CGSize)getImageSizeWithURL:(id)URL; /** * 根据图片url获取图片尺寸 */ + (CGSize)getImageSizeWithURL:(id)URL{ NSURL * url = nil; if ([URL isKindOfClass:[NSURL class]]) { url = URL; } if ([URL isKindOfClass:[NSString class]]) { url = [NSURL URLWithString:URL]; } if (!URL) { return CGSizeZero; } CGImageSourceRef imageSourceRef = CGImageSourceCreateWithURL((CFURLRef)url, NULL); CGFloat width = 0, height = 0; if (imageSourceRef) { CFDictionaryRef imageProperties = CGImageSourceCopyPropertiesAtIndex(imageSourceRef, 0, NULL); if (imageProperties != NULL) { CFNumberRef widthNumberRef = CFDictionaryGetValue(imageProperties, kCGImagePropertyPixelWidth); // if (widthNumberRef != NULL) { // CFNumberGetValue(widthNumberRef, kCFNumberFloat64Type, &width); // } // CFNumberRef heightNumberRef = CFDictionaryGetValue(imageProperties, kCGImagePropertyPixelHeight); // if (heightNumberRef != NULL) { // CFNumberGetValue(heightNumberRef, kCFNumberFloat64Type, &height); // } //判断设备是否为64位 #if defined(__LP64__) && __LP64__ if (widthNumberRef != NULL) { CFNumberGetValue(widthNumberRef, kCFNumberFloat64Type, &width); } CFNumberRef heightNumberRef = CFDictionaryGetValue(imageProperties, kCGImagePropertyPixelHeight); if (heightNumberRef != NULL) { CFNumberGetValue(heightNumberRef, kCFNumberFloat64Type, &height); } #else if (widthNumberRef != NULL) { CFNumberGetValue(widthNumberRef, kCFNumberFloat32Type, &width); } CFNumberRef heightNumberRef = CFDictionaryGetValue(imageProperties, kCGImagePropertyPixelHeight); if (heightNumberRef != NULL) { CFNumberGetValue(heightNumberRef, kCFNumberFloat32Type, &height); } #endif CFRelease(imageProperties); } CFRelease(imageSourceRef); } return CGSizeMake(width, height); }
实践证明,网上的另外一种方法是不可行存在问题的,贴上所示的图片url:http://xs3.op.xywy.com/club.xywy.com/doc/20181017/0fd2a51f9435a4.jpg
// 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; } } }
源自:https://www.jianshu.com/p/9984c37f3f54