在之前的开发中遇到一个需求 需要像http head 中增加客户端的类型 和版本号，下面就说说怎么加及 需要注意的一些细节：

 1 +(NSMutableURLRequest*)addHTTPRequestHeaderInfo:(NSURL*)requestUrl 2 {     3     NSMutableURLRequest *mutableRequest = [[[NSMutableURLRequest alloc]initWithURL:requestUrl]autorelease]; 4     NSDictionary *infoDict =[[NSBundle mainBundle] infoDictionary]; 5     NSString *versionNum =[infoDict stringForKey:@"CFBundleVersion"]; 6     NSString *appName =[infoDict stringForKey:@"CFBundleExecutable"]; 7     [mutableRequest addValue:appName forHTTPHeaderField:@"app-id"]; 8     [mutableRequest addValue:@"ios" forHTTPHeaderField:@"client-type"]; 9     [mutableRequest addValue:versionNum forHTTPHeaderField:@"app-version"];10     NSLog(@"%@", mutableRequest.allHTTPHeaderFields);11     return mutableRequest;12 }