获取image信息

NSData *data = UIImageJPEGRepresentation(image, 1.0);
CGImageSourceRef ref = CGImageSourceCreateWithData((__bridge CFDataRef)data, NULL);
CFDictionaryRef dicRef = CGImageSourceCopyPropertiesAtIndex(ref, 0, NULL);
NSDictionary *dic = CFBridgingRelease(dicRef);
NSLog(@"%@",dic);
CFRelease(ref);