Iphone 仅在显示警报视图时，Exc_错误访问

我有许多线程通过performLeachToRecainthread方法调用以下函数：

-(void) showAlert: (NSString *)message{
if ([NSRunLoop currentRunLoop] != [NSRunLoop mainRunLoop]) {
    NSLog(@"<< perform in main thread>>");
    [self performSelectorOnMainThread:@selector(showAlert:) withObject:message waitUntilDone:NO];
}
UIAlertView *alert = [[UIAlertView alloc]initWithTitle:@"Info" message:message delegate:nil cancelButtonTitle:@"OK" otherButtonTitles:nil];
[alert show];
}

-（void）showAlert:（NSString*）消息{
如果（[nsrunlop currentRunLoop]！=[nsrunlop mainRunLoop]）{
NSLog（@“>”）；
[self-performSelectorOnMainThread:@selector（showAlert:）with object:message waitUntilDone:NO]；
}
UIAlertView*alert=[[UIAlertView alloc]initWithTitle:@“信息”消息：消息委托：nil CancelButtontile:@“确定”其他Buttontiles:nil]；
[警报显示]；
}

因为，在任何情况下，此方法都将仅在主线程上调用，所以我不知道EXC_BAD_ACCESS崩溃的原因： [警报显示]

---

而这种崩溃只是偶尔发生的。请提供帮助。

问题在于如果条件为真或假，则alertview显示方法将起作用。 更改您的方法，如：

-(void) showAlert: (NSString *)message
{
 if ([NSRunLoop currentRunLoop] != [NSRunLoop mainRunLoop])
 {
    NSLog(@"<< perform in main thread>>");
    [self performSelectorOnMainThread:@selector(showAlert:) withObject:message waitUntilDone:NO];
 }
 else
 {
   UIAlertView *alert = [[UIAlertView alloc]initWithTitle:@"Info" message:message delegate:nil cancelButtonTitle:@"OK" otherButtonTitles:nil];
  [alert show];
 }
}

-（void）showAlert:（NSString*）消息
{
如果（[nsrunlop currentRunLoop]！=[nsrunlop mainRunLoop]）
{
NSLog（@“>”）；
[self-performSelectorOnMainThread:@selector（showAlert:）with object:message waitUntilDone:NO]；
}
其他的
{
UIAlertView*alert=[[UIAlertView alloc]initWithTitle:@“信息”消息：消息委托：nil CancelButtontile:@“确定”其他Buttontiles:nil]；
[警报显示]；
}
}

我猜你忘了添加

返回在代码中，这样无论是否在主循环中，if下面的代码都会被执行

一个简单的解决方案可能是：

-(void) showAlert: (NSString *)message{
    if ([NSRunLoop currentRunLoop] != [NSRunLoop mainRunLoop]) {
        NSLog(@"<< perform in main thread>>");
        [self performSelectorOnMainThread:@selector(showAlert:) withObject:message waitUntilDone:NO];
        return;
    }
    UIAlertView *alert = [[UIAlertView alloc]initWithTitle:@"Info" message:message delegate:nil cancelButtonTitle:@"OK" otherButtonTitles:nil];
    [alert show];
}

-（void）showAlert:（NSString*）消息{
如果（[nsrunlop currentRunLoop]！=[nsrunlop mainRunLoop]）{
NSLog（@“>”）；
[self-performSelectorOnMainThread:@selector（showAlert:）with object:message waitUntilDone:NO]；
返回；
}
UIAlertView*alert=[[UIAlertView alloc]initWithTitle:@“信息”消息：消息委托：nil CancelButtontile:@“确定”其他Buttontiles:nil]；
[警报显示]；
}
在if块的末尾放置一个
返回值
：

-(void) showAlert: (NSString *)message{
if ([NSRunLoop currentRunLoop] != [NSRunLoop mainRunLoop]) {
    NSLog(@"<< perform in main thread>>");
    [self performSelectorOnMainThread:@selector(showAlert:) withObject:message waitUntilDone:NO];
    return;
}
UIAlertView *alert = [[UIAlertView alloc]initWithTitle:@"Info" message:message delegate:nil cancelButtonTitle:@"OK" otherButtonTitles:nil];
[alert show];
}

-（void）showAlert:（NSString*）消息{
如果（[nsrunlop currentRunLoop]！=[nsrunlop mainRunLoop]）{
NSLog（@“>”）；
[self-performSelectorOnMainThread:@selector（showAlert:）with object:message waitUntilDone:NO]；
返回；
}
UIAlertView*alert=[[UIAlertView alloc]initWithTitle:@“信息”消息：消息委托：nil CancelButtontile:@“确定”其他Buttontiles:nil]；
[警报显示]；
}
备选方案为什么不使用此选项：

 [alert performSelectorOnMainThread:@selector(show) withObject:nil waitUntilDone:YES];

而不是

 [alert show];