iOS 網(wǎng)絡(luò)訪問(wèn)

• 蘋(píng)果 API
  • NSURLConnection
    iOS 9.0 之后就會(huì)建議使用 NSURLSession "Use NSURLSession (see NSURLSession.h)")
  • NSURLSession（iOS 7.0）
  • CFNetwork（底層實(shí)現(xiàn)）
• 第三方框架
  • AFNetworking
  • ASI
    這個(gè)可能很多人已經(jīng)不用了茎活，因?yàn)樽髡咭呀?jīng)不再更新了，但是 ASI 的下載還是很好用的琢唾，而且 ASI 是通過(guò) CFNetwork 實(shí)現(xiàn)的载荔，首先效率很高，而且底層本來(lái)就很穩(wěn)定采桃，不更新也是很正常的

NSURLConnection

    NSURL *url = [NSURL     NSURL *url = [NSURL URLWithString:@"http://www.baidu.com"];
    
    NSURLRequest *request = [NSURLRequest requestWithURL:url];
    // 需要修改請(qǐng)求頭或者請(qǐng)求體的時(shí)候懒熙，需要的是 mutable URL request
    NSMutableURLRequest *requestM = [[NSMutableURLRequest alloc] initWithURL:url];
    [requestM setValue:@"iPhone AppleWebKit" forHTTPHeaderField:@"User_Agent"];
    
    __weak typeof(self) weakSelf = self;
    // requestM 打開(kāi)的才是移動(dòng)端的網(wǎng)頁(yè)
    [NSURLConnection sendAsynchronousRequest:request queue:[NSOperationQueue mainQueue] completionHandler:^(NSURLResponse * _Nullable response, NSData * _Nullable data, NSError * _Nullable connectionError) {
        if (connectionError == nil && data.length > 0) {
            NSString *html = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
            [weakSelf.webView loadHTMLString:html baseURL:url];
        }
    }];

代碼其實(shí)挺簡(jiǎn)單的，而且 NSURLConnection 已經(jīng) 9.0 棄用了普办，如果還有想要嘗試的童鞋還是可以看看的工扎，畢竟是蘋(píng)果最早處理網(wǎng)絡(luò)訪問(wèn)的方法。
一般 connection 都會(huì)異步發(fā)送請(qǐng)求衔蹲，但是也有同步的時(shí)候肢娘，比如斷點(diǎn)續(xù)傳，下載文件之前需要知道上次下載文件大小舆驶，就可以同步發(fā)送請(qǐng)求橱健，而且可以發(fā)送 HEAD 請(qǐng)求。
HEAD 請(qǐng)求

    NSURL *url = [NSURL URLWithString:@"http://127.0.0.1/videos.zip"];
    NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:url];
    // HEAD 請(qǐng)求不會(huì)返回響應(yīng)體贞远，只是返回響應(yīng)頭畴博，可以查看數(shù)據(jù)大小
    request.HTTPMethod = @"HEAD";
    NSURLResponse *response = nil;
    NSData *data = [NSURLConnection sendSynchronousRequest:request returningResponse:&response error:NULL];
    NSLog(@"HEAD response head -- %zd", response.expectedContentLength);
    NSLog(@"HEAD response body -- %zd", data.length);

P.S.(Postscript)

GET 請(qǐng)求

    NSURL *url = [NSURL URLWithString:@"http://127.0.0.1/login.php?username=username+&password=pwd"];
    NSURLRequest *request = [NSURLRequest requestWithURL:url];
    [NSURLConnection sendAsynchronousRequest:request queue:[NSOperationQueue mainQueue] completionHandler:^(NSURLResponse * _Nullable response, NSData * _Nullable data, NSError * _Nullable connectionError) {
        if (connectionError == nil && data.length > 0) {
            NSDictionary *dict = [NSJSONSerialization JSONObjectWithData:data options:0 error:NULL];
            NSLog(@"%@", dict);
        } else {
            NSLog(@"%@", connectionError);
        }
    }];

POST 請(qǐng)求

    NSURL *url = [NSURL URLWithString:@"http://127.0.0.1/login.php"];
    NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:url];
    // 默認(rèn)是通過(guò) GET 發(fā)送請(qǐng)求
    request.HTTPMethod = @"POST";
    NSString *requestBodyString = @"username=username&password=pwd";
    NSData *requestBody = [requestBodyString dataUsingEncoding:NSUTF8StringEncoding];
    request.HTTPBody = requestBody;
    [NSURLConnection sendAsynchronousRequest:request queue:[NSOperationQueue mainQueue] completionHandler:^(NSURLResponse * _Nullable response, NSData * _Nullable data, NSError * _Nullable connectionError) {
        if (connectionError == nil && data.length > 0) {
            NSDictionary *dict = [NSJSONSerialization JSONObjectWithData:data options:0 error:NULL];
            NSLog(@"%@", dict);
        } else {
            NSLog(@"%@", connectionError);
        }
    }];