如何在AfNetworking 3.0中为请求添加Header？

// 导入AfNetworking库
#import <AFNetworking/AFNetworking.h>

// 创建请求管理器
AFHTTPSessionManager *manager = [AFHTTPSessionManager manager];

// 创建请求对象
NSURL *url = [NSURL URLWithString:@"http://example.com/api"];
NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:url];

// 添加Header
[request setValue:@"headerValue" forHTTPHeaderField:@"headerField"];

// 发送请求
NSURLSessionDataTask *task = [manager dataTaskWithRequest:request completionHandler:^(NSURLResponse *response, id responseObject, NSError *error) {
    if (error) {
        NSLog(@"Error: %@", error);
    } else {
        NSLog(@"Response: %@", responseObject);
    }
}];
[task resume];