iOS中的JSON请求-使用Grand Central Dispatch或NSURLConnection [英] JSON requests in iOS - use Grand Central Dispatch or NSURLConnection

问题描述

我看到了一些有关在iOS中进行JSON请求的教程，其中许多教程都使用NSURLConnection列出了类似的内容:

I saw several tutorials on making JSON requests in iOS, many of them listed something like this using NSURLConnection:

- (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response {
    [self.responseData setLength:0];
}

- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data {
    [self.responseData appendData:data];
}

- (void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error {
    NSLog([NSString stringWithFormat:@"Connection failed: %@", [error description]]);
}

- (void)connectionDidFinishLoading:(NSURLConnection *)connection {}

但是我今天又读了另一篇教程( http://mobile.tutsplus.com/tutorials/iphone/ios-quick-tip-interacting-with-web-services/)在此实现了非常简单的实现:

But I read another tutorial today (http://mobile.tutsplus.com/tutorials/iphone/ios-quick-tip-interacting-with-web-services/) where it had this beautifully simple implementation:

dispatch_queue_t queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);
dispatch_async(queue, ^{
    NSError *error = nil;
    NSURL *url = [NSURL URLWithString:@"http://brandontreb.com/apps/pocket-mud-pro/promo.json"];
    NSString *json = [NSString stringWithContentsOfURL:url
                                              encoding:NSASCIIStringEncoding
                                                 error:&error];
    NSLog(@"\nJSON: %@ \n Error: %@", json, error);
});

哪个会更好?后者的简单性有天生的错误吗?

Which one would be better to use? Is there one inherently wrong with the simplicity of the latter?

推荐答案

使用stringWithContentsOfURL:encoding:error:并没有什么错"，但是您在处理正在进行的请求时没有灵活性.如果您需要执行以下任一操作，则可以使用NSURLConnection:

There is nothing "wrong" with the using stringWithContentsOfURL:encoding:error: but you have no flexibility in how you handle a request in progress. If you need to do any of the following then I would use NSURLConnection:

1. 在请求期间向用户显示完成百分比
2. 向需要HTTP身份验证的主机执行请求
3. 更复杂的数据处理(例如，从Web服务下载的数据比典型的JSON响应要多)，您可能需要分块处理响应
4. 取消请求(感谢@martin)

这篇关于iOS中的JSON请求-使用Grand Central Dispatch或NSURLConnection的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！