微博开放平台

使用OAuth2
1.获取新浪的登录界面（UIWebView）
2.登陆成功后，会从服务器获取一个状态码（code）
3.用code向服务器换取一个accessToken令牌

//登陆
- (IBAction)loginBtnDidClicked:(UIButton *)sender {
    //1.使用OAuth2/authorize发起请求
    NSString *urlString = [NSString stringWithFormat:@"https://api.weibo.com/oauth2/authorize?client_id=%@&redirect_uri=%@", kAppKey, kRedirect_uri];
    NSURL *url = [NSURL URLWithString:urlString];
    
    //创建请求
    NSURLRequest *request = [NSURLRequest requestWithURL:url cachePolicy:NSURLRequestReloadIgnoringLocalAndRemoteCacheData timeoutInterval:60];
    
    //使用UIWebView加载页面
    self.webView = [[UIWebView alloc] initWithFrame:self.view.bounds];
    _webView.delegate = self;
    [self.view addSubview:_webView];
    [_webView loadRequest:request];
}

- (BOOL)webView:(UIWebView *)webView shouldStartLoadWithRequest:(NSURLRequest *)request navigationType:(UIWebViewNavigationType)navigationType{
    //目标：获取code的状态码
    //解决方案：对即将加载的request对应的URL进行解析，一旦URL里面包含code=，那么就停止
    if ([[request.URL relativeString] containsString:@"code="]) {
        //说明此刻即将请求的request里面包含了code
        NSRange range  = [[request.URL relativeString] rangeOfString:@"code="];
        NSString *code = [[request.URL relativeString] substringFromIndex:range.location + range.length];
        
        //关闭webView
        [_webView removeFromSuperview];
        
        //使用这个code去换取一个accessToken令牌
        //解决方案，向服务器发送一个POST请求
        NSURL *codeURL = [NSURL URLWithString:@"https://api.weibo.com/oauth2/access_token"];
        //创建一个可变请求（因为要修改头部信息）
        NSMutableURLRequest *codeResquest = [NSMutableURLRequest requestWithURL:codeURL];
        
        //设置请求方式为POST
        [codeResquest setHTTPMethod:@"POST"];
        
        //准备上传的数据
        NSString *dataString = [NSString stringWithFormat:@"client_id=%@&client_secret=%@&grant_type=authorization_code&code=%@&redirect_uri=%@", kAppKey, kAppSecret, code, kRedirect_uri];
        NSData *upData = [dataString dataUsingEncoding:NSUTF8StringEncoding];
        
        //创建session
        NSURLSession *session = [NSURLSession sharedSession];;
        NSURLSessionUploadTask *uploadTask = [session uploadTaskWithRequest:codeResquest fromData:upData completionHandler:^(NSData * _Nullable data, NSURLResponse * _Nullable response, NSError * _Nullable error) {
            //NSData -> NSDictionary
            NSDictionary *resultDic = [NSJSONSerialization JSONObjectWithData:data options:NSJSONReadingMutableContainers error:&error];
            
            //保存access_token expires_in uid
            NSString *accessToken = [resultDic objectForKey:@"access_token"];
            NSString *expiresIn   = [resultDic objectForKey:@"expires_in"];
            NSString *uid         = [resultDic objectForKey:@"uid"];
            
            NSUserDefaults *userDefaults = [NSUserDefaults standardUserDefaults];
            [userDefaults setObject:accessToken forKey:kAccessTokenKey];
            [userDefaults setObject:expiresIn forKey:kExpiresTimeKey];
            [userDefaults setObject:uid forKey:kUserIDKey];
            [userDefaults synchronize];
            }];
        
        [uploadTask resume];
        return NO;
    } else{
        return YES;
    }
}