用戶點擊後立即顯示活動指示燈代替登錄按鈕

Question

我想在我的應用程序正在檢查用戶身份驗證時顯示一個活動指示符來代替我的右邊UIBarButtonItem。

目前發生了什麼，用戶是否單擊登錄按鈕，然後用戶界面暫停並等待網絡電話返回。已建議我使用一個調度隊列在不同的線程運行這個，但是我不知道如何將這些兩段代碼結合起來：

調度隊列：

dispatch_queue_t queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0); 
dispatch_async(queue,^{ 
//show your indicator button 
dispatch_async(dispatch_get_main_queue(),^{ 
    //stop indicator when user has logged in 
}); 
}); 

登錄方法：

- (void) loginAction{ 

UIActivityIndicatorView *activityIndicator = [[UIActivityIndicatorView alloc] 
initWithFrame:CGRectMake(0, 0, 20, 20)]; 
[activityIndicator startAnimating]; 
UIBarButtonItem *activityItem = [[UIBarButtonItem alloc] 
initWithCustomView:activityIndicator]; 
self.navigationItem.rightBarButtonItem = activityItem; 

if ([userNameTextField.text isEqualToString:@""] || [passwordTextField.text 
isEqualToString:@""]) { 

UIBarButtonItem *btnGo = [[UIBarButtonItem alloc] initWithTitle:@"Login" 
style:UIBarButtonItemStyleBordered target:self action:@selector(loginAction)]; 
self.navigationItem.rightBarButtonItem = btnGo; 
[self.navigationItem.rightBarButtonItem setTintColor:[UIColor colorWithRed:44.0/255.0 
green:160.0/255.0 blue:65.0/255.0 alpha:1.0]]; 

UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Invalid Login" message:@"" 
delegate:self cancelButtonTitle:@"OK" otherButtonTitles:nil, nil]; 
[alert show]; 
    return; 
} 

if (loginSuccess== true) { 

    //continue 
} 

}else 
{ 
UIBarButtonItem *btnGo = [[UIBarButtonItem alloc] initWithTitle:@"Login" 
style:UIBarButtonItemStyleBordered target:self action:@selector(loginAction)]; 
self.navigationItem.rightBarButtonItem = btnGo; 
[self.navigationItem.rightBarButtonItem setTintColor:[UIColor colorWithRed:44.0/255.0 
green:160.0/255.0 blue:65.0/255.0 alpha:1.0]]; 

UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Invalid Login" message:@"" 
delegate:self cancelButtonTitle:@"OK" otherButtonTitles:nil, nil]; 
[alert show]; 
return; 

} 
} 

Answer 1

我遇到了同樣的問題。我已經修復這樣。在viewdidload中，我添加了活動指示器作爲子視圖，並在點擊登錄按鈕時開始動畫指示器。然後用performSelector我調用了一個包含登錄服務調用的方法，最後我停止了指示器。它爲我工作很好。使用此代碼..

.h UIActivityIndi​​catorView * activityIndi​​cator;

在.M

- (void)viewDidLoad 
{ 

    [super viewDidLoad]; 

    activityIndicator = [[UIActivityIndicatorView alloc] initWithActivityIndicatorStyle:UIActivityIndicatorViewStyleWhiteLarge]; 
    [activityIndicator setFrame:CGRectMake(0, 0, 37, 37)]; 
    [activityIndicator setCenter:self.view.center]; 
    [activityIndicator setHidesWhenStopped:YES]; 
    [self.view addSubview:activityIndicator]; 
    [self setDisplayStatusOfControls]; 

} 


    -(IBAction)loginButton 
    { 

    [activityIndicator startAnimating]; 
    [self performSelector:@selector(Loginauthentication) withObject:nil afterDelay:0.1f]; 

    } 

- (void) loginAction 
{ 
//Log in authentication.. 



[activityIndicator stopAnimating]; 
} 

Answer 2

做這樣的事情：

dispatch_queue_t queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0); 
dispatch_async(queue,^{ 
    //show your indicator button 
    dispatch_async(dispatch_get_main_queue(),^{ 
     //stop indicator when user has logged in 
    }); 
}); 

Answer 3

UI只能在主線程上更新。當主線程正在做別的事情時，用戶界面無法更新。要更新您的活動指標，您可以執行以下操作：

[self performSelectorOnMainThread:@selector(loginAction:) withObject:anObject waitUntilDone:NO];