本文轉載至?http://blog.csdn.net/liuwuguigui/article/details/39494597 IOS8UIAlertViewUIActionSheet

iOS8推出了幾個新的“controller”，主要是把類似之前的UIAlertView變成了UIAlertController，這不經意的改變，貌似把我之前理解的“controller”一下子推翻了～但是也無所謂，有新東西不怕，學會使用了就行。接下來會探討一下這些個新的Controller。

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- (void)showOkayCancelAlert {NSString *title = NSLocalizedString(@"A Short Title Is Best", nil);NSString *message = NSLocalizedString(@"A message should be a short, complete sentence.", nil);NSString *cancelButtonTitle = NSLocalizedString(@"Cancel", nil);NSString *otherButtonTitle = NSLocalizedString(@"OK", nil);UIAlertController *alertController = [UIAlertController alertControllerWithTitle:title message:message preferredStyle:UIAlertControllerStyleAlert];// Create the actions.UIAlertAction *cancelAction = [UIAlertAction actionWithTitle:cancelButtonTitle style:UIAlertActionStyleCancel handler:^(UIAlertAction *action) {NSLog(@"The \"Okay/Cancel\" alert's cancel action occured.");}];UIAlertAction *otherAction = [UIAlertAction actionWithTitle:otherButtonTitle style:UIAlertActionStyleDefault handler:^(UIAlertAction *action) {NSLog(@"The \"Okay/Cancel\" alert's other action occured.");}];// Add the actions.[alertController addAction:cancelAction];[alertController addAction:otherAction];[self presentViewController:alertController animated:YES completion:nil]; }

這是最普通的一個alertcontroller，一個取消按鈕，一個確定按鈕。

新的alertcontroller，其初始化方法也不一樣了，按鈕響應方法綁定使用了block方式，有利有弊。需要注意的是不要因為block導致了引用循環，記得使用__weak，尤其是使用到self。

上面的界面如下：

如果UIAlertAction *otherAction這種otherAction多幾個的話，它會自動排列成如下：

另外，很多時候，我們需要在alertcontroller中添加一個輸入框，例如輸入密碼：

這時候可以添加如下代碼：

[alertController addTextFieldWithConfigurationHandler:^(UITextField *textField) {// 可以在這里對textfield進行定制，例如改變背景色textField.backgroundColor = [UIColor orangeColor];}];

而改變背景色會這樣：

完整的密碼輸入：

- (void)showSecureTextEntryAlert {NSString *title = NSLocalizedString(@"A Short Title Is Best", nil);NSString *message = NSLocalizedString(@"A message should be a short, complete sentence.", nil);NSString *cancelButtonTitle = NSLocalizedString(@"Cancel", nil);NSString *otherButtonTitle = NSLocalizedString(@"OK", nil);UIAlertController *alertController = [UIAlertController alertControllerWithTitle:title message:message preferredStyle:UIAlertControllerStyleAlert];// Add the text field for the secure text entry.[alertController addTextFieldWithConfigurationHandler:^(UITextField *textField) {// Listen for changes to the text field's text so that we can toggle the current// action's enabled property based on whether the user has entered a sufficiently// secure entry.[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(handleTextFieldTextDidChangeNotification:) name:UITextFieldTextDidChangeNotification object:textField];textField.secureTextEntry = YES;}];// Create the actions.UIAlertAction *cancelAction = [UIAlertAction actionWithTitle:cancelButtonTitle style:UIAlertActionStyleCancel handler:^(UIAlertAction *action) {NSLog(@"The \"Secure Text Entry\" alert's cancel action occured.");// Stop listening for text changed notifications.[[NSNotificationCenter defaultCenter] removeObserver:self name:UITextFieldTextDidChangeNotification object:alertController.textFields.firstObject];}];UIAlertAction *otherAction = [UIAlertAction actionWithTitle:otherButtonTitle style:UIAlertActionStyleDefault handler:^(UIAlertAction *action) {NSLog(@"The \"Secure Text Entry\" alert's other action occured.");// Stop listening for text changed notifications.[[NSNotificationCenter defaultCenter] removeObserver:self name:UITextFieldTextDidChangeNotification object:alertController.textFields.firstObject];}];// The text field initially has no text in the text field, so we'll disable it.otherAction.enabled = NO;// Hold onto the secure text alert action to toggle the enabled/disabled state when the text changed.self.secureTextAlertAction = otherAction;// Add the actions.[alertController addAction:cancelAction];[alertController addAction:otherAction];[self presentViewController:alertController animated:YES completion:nil]; }

注意四點：

1.添加通知，監聽textfield內容的改變：

// Add the text field for the secure text entry.[alertController addTextFieldWithConfigurationHandler:^(UITextField *textField) {// Listen for changes to the text field's text so that we can toggle the current// action's enabled property based on whether the user has entered a sufficiently// secure entry.[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(handleTextFieldTextDidChangeNotification:) name:UITextFieldTextDidChangeNotification object:textField];textField.secureTextEntry = YES;}];

2.初始化時候，禁用“ok”按鈕：

otherAction.enabled = NO;

self.secureTextAlertAction = otherAction;//定義一個全局變量來存儲

3.當輸入超過5個字符時候，使self.secureTextAlertAction ＝ YES：

- (void)handleTextFieldTextDidChangeNotification:(NSNotification *)notification {UITextField *textField = notification.object;// Enforce a minimum length of >= 5 characters for secure text alerts.self.secureTextAlertAction.enabled = textField.text.length >= 5; }

4.在“OK”action中去掉通知：

UIAlertAction *otherAction = [UIAlertAction actionWithTitle:otherButtonTitle style:UIAlertActionStyleDefault handler:^(UIAlertAction *action) {NSLog(@"The \"Secure Text Entry\" alert's other action occured.");// Stop listening for text changed notifications.[[NSNotificationCenter defaultCenter] removeObserver:self name:UITextFieldTextDidChangeNotification object:alertController.textFields.firstObject];}];

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最后是以前經常是alertview與actionsheet結合使用，這里同樣也有：

- (void)showOkayCancelActionSheet {NSString *cancelButtonTitle = NSLocalizedString(@"Cancel", nil);NSString *destructiveButtonTitle = NSLocalizedString(@"OK", nil);UIAlertController *alertController = [UIAlertController alertControllerWithTitle:nil message:nil preferredStyle:UIAlertControllerStyleActionSheet];// Create the actions.UIAlertAction *cancelAction = [UIAlertAction actionWithTitle:cancelButtonTitle style:UIAlertActionStyleCancel handler:^(UIAlertAction *action) {NSLog(@"The \"Okay/Cancel\" alert action sheet's cancel action occured.");}];UIAlertAction *destructiveAction = [UIAlertAction actionWithTitle:destructiveButtonTitle style:UIAlertActionStyleDestructive handler:^(UIAlertAction *action) {NSLog(@"The \"Okay/Cancel\" alert action sheet's destructive action occured.");}];// Add the actions.[alertController addAction:cancelAction];[alertController addAction:destructiveAction];[self presentViewController:alertController animated:YES completion:nil]; }

在底部顯示如下：

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好了，至此，基本就知道這個新的controller到底是怎樣使用了。

總結

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