我是iOS开发新手。我已经搜索并尝试了几种方法，但是该程序不想等待异步调用完成。
调试时，函数CheckForHost首先返回-1作为retVal。这将导致调用该函数的方法继续。一秒钟后，程序返回到CheckForHost函数，将正确的值设置为retVal。我也尝试过NSCondition但也没有运气...
有人可以告诉我我做错了还是应该做不同的事情？非常感谢您的帮助！
下面的代码：
-(int)CheckForHost
{
InternetActive = -1;
HostActive = -1;
dispatch_queue_t myQueue = dispatch_queue_create("my queue", NULL);
__block int retVal = -1;
dispatch_async(myQueue, ^{
[self HostInit];
dispatch_async(dispatch_get_main_queue(), ^{
[internetReachable stopNotifier];
[hostReachable stopNotifier];
[[NSNotificationCenter defaultCenter] removeObserver:self];
if (InternetActive == 0) {
retVal = 0;
} else if (HostActive == 0) {
retVal = 1;
} else
retVal = 2;
});
});
return retVal;
}
-(void)HostInit
{
// check for internet connection
[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(checkNetworkStatus:) name:kReachabilityChangedNotification object:nil];
internetReachable = [Reachability reachabilityForInternetConnection];
[internetReachable startNotifier];
// check if a pathway to a random host exists
hostReachable = [Reachability reachabilityWithHostName:@"www.apple.com"];
[hostReachable startNotifier];
// now patiently wait for the notification
}
-(void)checkNetworkStatus:(NSNotification *)notice
{
// called after network status changes
NetworkStatus internetStatus = [internetReachable currentReachabilityStatus];
switch (internetStatus)
{
case NotReachable:
{
NSLog(@"The internet is down.");
InternetActive = 0;
break;
}
case ReachableViaWiFi:
{
NSLog(@"The internet is working via WIFI.");
InternetActive = 1;
break;
}
case ReachableViaWWAN:
{
NSLog(@"The internet is working via WWAN.");
InternetActive = 1;
break;
}
}
NetworkStatus hostStatus = [hostReachable currentReachabilityStatus];
switch (hostStatus)
{
case NotReachable:
{
NSLog(@"A gateway to the host server is down.");
HostActive = 0;
break;
}
case ReachableViaWiFi:
{
NSLog(@"A gateway to the host server is working via WIFI.");
HostActive = 1;
break;
}
case ReachableViaWWAN:
{
NSLog(@"A gateway to the host server is working via WWAN.");
HostActive = 1;
break;
}
}
}我会使用积木，它们既简单又可靠
这是带有block的函数的示例：
- (void)checkForHostWithBlock:(void (^)(int myReturnedInt))completion{
//Our function does stuff here, i'll copy paste some of your code
InternetActive = -1;
HostActive = -1;
dispatch_queue_t myQueue = dispatch_queue_create("my queue", NULL);
__block int retVal = -1;
dispatch_async(myQueue, ^{
[self HostInit];
dispatch_async(dispatch_get_main_queue(), ^{
[internetReachable stopNotifier];
[hostReachable stopNotifier];
[[NSNotificationCenter defaultCenter] removeObserver:self];
if (InternetActive == 0) {
retVal = 0;
} else if (HostActive == 0) {
retVal = 1;
} else
retVal = 2;
if (completion){
completion(retVal);
}
});
});
}
妳去
您可以像调用其他任何方法一样调用该方法，并且可以使用自动完成功能来确保正确记录所有内容。
[self checkForHostWithBlock:^(int myReturnInt){
//Executed code when the block is called in checkForHost:
NSLog(@"Here is my int : %i !!", myReturnInt);
}];
请注意，block参数可以为nil，但是您需要确保随后在方法中对其进行检查。
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我来说两句