克服 NSURL 的 checkResourceIsReachableAndReturnError 的意外行为 [英] Overcoming unexpected behavior of NSURL's checkResourceIsReachableAndReturnError

问题描述

在我为 iOS 5 创建的程序中，我遇到了 NSURL 的 checkResourceIsReachableAndReturnError 方法的意外行为.

In a program I am creating for iOS 5, I am experiencing unexpected behavior with the checkResourceIsReachableAndReturnError method of NSURL.

我创建了一个新项目来验证问题并且只包含代码:

I created a new project to verify the issue and included only the code:

NSURL *url = [NSURL URLWithString:@"http://www.stackoverflow.com"];
NSError *err = nil;
if([url checkResourceIsReachableAndReturnError:&err]){
  NSLog(@"URL is reachable");
}else {
 NSLog(@"URL is not reachable");
}

进一步，我试过:

NSURL *url = [NSURL URLWithString:@"http://www.stackoverflow.com"];
NSError *err = nil;
[url checkResourceIsReachableAndReturnError:&err];
if(err == nil){
 NSLog(@"URL is reachable");
}else {
 NSLog(@"URL is not reachable");
}

...仍然无济于事.结果总是URL 无法访问"，这与 stackoverflow.com(以及我测试的其他域)显然可以访问相反.如何利用这个函数来检查资源是否可达?

...still to no avail. The result is always, "URL is not reachable", contrary to stackoverflow.com (and other domains I tested) obviously being reachable. How does one utilize this function to check if a resource is reachable?

推荐答案

Apple 文档 checkResourceIsReachableAndReturnError: 状态:

Returns whether the resource pointed to by a file URL can be reached.

注意:文件 URL"，而不是 Internet 或其他方案 URL.

Note: "file URL", not Internet or other scheme URL.

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