除非我註釋掉自動解除，否則看不到我的alertView

Question

我正在實現一個簡單的警報視圖，並在應用程序執行數據庫還原時向用戶顯示活動指示器。一切都很好，除非我看不到警報視圖，除非我註釋掉自動解僱行（這裏是最後一行）。

好吧，數據庫的還原是相當快的，但我仍然期望看到它，即使是瞬間的，不是？在動畫期間，我可以看到屏幕變得更暗，但這就是全部。我也嘗試了一個for循環來延長時間，時間延長但仍然沒有警報視圖。

警告視圖被調用的方式沒有錯，因爲如果我評論解僱，我可以看到它......只有永遠。任何人有一個想法嗎？

在任何人說出來之前，我試着改變alertView的代表爲self，發佈爲here，但它沒有幫助。

// First we prepare the activity indicator view to show progress indicator 
UIActivityIndicatorView * activityView = [[UIActivityIndicatorView alloc] initWithActivityIndicatorStyle:UIActivityIndicatorViewStyleWhiteLarge]; 

[activityView setFrame:CGRectMake(121.0f, 50.0f, 37.0f, 37.0f)]; 
[activityView startAnimating]; 

// Then we put it in an alert view 
UIAlertView *alertView = [[UIAlertView alloc] initWithTitle:@"Loading" message:nil delegate:nil cancelButtonTitle:nil otherButtonTitles:nil]; 
[alertView addSubview:activityView]; 
[alertView show]; 

// Finally we operate the restore 
[[SQLManager sharedSQL] restoreDatabase:[restoreDatabaseURL path]]; 

// And we can dismiss the alert view with the progress indicator 
[alertView dismissWithClickedButtonIndex:0 animated:NO]; 

Answer 1

林不知道爲什麼這發生，但我遇到它偶爾也。我已經得到了這樣的工作的一種方法是通過下一次調用使用performSelector:withObject:afterDelay:，像這樣：

// First we prepare the activity indicator view to show progress indicator 
UIActivityIndicatorView * activityView = [[UIActivityIndicatorView alloc] initWithActivityIndicatorStyle:UIActivityIndicatorViewStyleWhiteLarge]; 

[activityView setFrame:CGRectMake(121.0f, 50.0f, 37.0f, 37.0f)]; 
[activityView startAnimating]; 

// Then we put it in an alert view 
UIAlertView *alertView = [[UIAlertView alloc] initWithTitle:@"Loading" message:nil delegate:nil cancelButtonTitle:nil otherButtonTitles:nil]; 
[alertView addSubview:activityView]; 
[alertView show]; 

// Finally we operate the restore 
// [[SQLManager sharedSQL] restoreDatabase:[restoreDatabaseURL path]]; 
[[SQLManager sharedSQL] performSelector:@selector(restoreDatabase:) withObject:[restoreDatabaseURL path] afterDelay:0.25]; 


// And we can dismiss the alert view with the progress indicator 
[alertView dismissWithClickedButtonIndex:0 animated:NO]; 

performSelector Documentation

Answer 2

聽起來像它本身解僱幾乎瞬間。如果你添加一個for循環，它可能會凍結所有其他的計算，這意味着你的活動視圖不會顯示直到循環中斷。

您可以嘗試使用NSTimer調用另一個函數來確定還原是否完成;

// Setup our the timer 
NSTimer *timer = [NSTimer scheduledTimerWithTimeInterval:1.0 
                target:self 
               selector:@selector(checkRestore) 
               userInfo:nil 
               repeats:YES]; 


// Timer function checking for completion 
-(void)checkRestore { 
    if (restore is complete) { 
     [alertView dismissWithClickedButtonIndex:0 animated:NO]; 
    } 
}