测试NSURLConnection与HTTP响应错误状态的使用

NSURL *url = [NSURL URLWithString:@"https://www.example.com"];
NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:url];

NSError *error = nil;
NSHTTPURLResponse *response = nil;
NSData *data = [NSURLConnection sendSynchronousRequest:request returningResponse:&response error:&error];

if (error) {
    // 请求失败
    NSLog(@"请求失败：%@", error.localizedDescription);
} else {
    // 请求成功
    NSInteger statusCode = response.statusCode;
    if (statusCode >= 200 && statusCode < 300) {
        // 请求成功
        NSLog(@"请求成功，状态码：%ld", (long)statusCode);
    } else if (statusCode >= 300 && statusCode < 400) {
        // 重定向
        NSLog(@"请求重定向，状态码：%ld", (long)statusCode);
    } else if (statusCode >= 400 && statusCode < 500) {
        // 客户端错误
        NSLog(@"客户端错误，状态码：%ld", (long)statusCode);
    } else if (statusCode >= 500 && statusCode < 600) {
        // 服务器错误
        NSLog(@"服务器错误，状态码：%ld", (long)statusCode);
    }
}