IOS-UIAlertController(UIAlertView和UIActionSheet二合一)

iOS8推出了几个新的“controller”，主要是把类似之前的UIAlertView变成了UIAlertController，这不经意的改变，貌似把我之前理解的“controller”一下子推翻了～但是也无所谓，有新东西不怕，学会使用了就行。接下来会探讨一下这些个新的Controller。

- (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];
}

这是最普通的一个alertcontroller，一个取消按钮，一个确定按钮。

新的alertcontroller，其初始化方法也不一样了，按钮响应方法绑定使用了block方式，有利有弊。需要注意的是不要因为block导致了引用循环，记得使用__weak，尤其是使用到self。

上面的界面如下：



如果UIAlertAction *otherAction这种otherAction多几个的话，它会自动排列成如下：



另外，很多时候，我们需要在alertcontroller中添加一个输入框，例如输入密码：



这时候可以添加如下代码：

[alertController addTextFieldWithConfigurationHandler:^(UITextField *textField) {
// 可以在这里对textfield进行定制，例如改变背景色
textField.backgroundColor = [UIColor orangeColor];
}];

而改变背景色会这样：



完整的密码输入：

- (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];
}
复制代码
注意四点：
1.添加通知，监听textfield内容的改变：
复制代码
// 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;
}];
复制代码
2.初始化时候，禁用“ok”按钮：
otherAction.enabled = NO;
self.secureTextAlertAction = otherAction;//定义一个全局变量来存储
3.当输入超过5个字符时候，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：
复制代码
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];
}];
复制代码

最后是以前经常是alertview与actionsheet结合使用，这里同样也有：
复制代码
- (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];
}

在底部显示如下：



好了，至此，基本就知道这个新的controller到底是怎样使用了。
--------------------------------------------------------------------------------------------------------------------------------------------------
我看博主上面用的是通知，感觉很是麻烦要调过来调过去的，在想直接传值应该也是可以的，自己试了一下，果然可以，嘻嘻！

- (IBAction)playlistCreateClick:(id)sender {
NSString *title = NSLocalizedString(@"createNewPlaylist", nil);
NSString *cancelButtonTitle = NSLocalizedString(@"Cancel", nil);
NSString *otherButtonTitle = NSLocalizedString(@"Save", nil);

UIAlertController *alertController = [UIAlertController alertControllerWithTitle:title message:nil preferredStyle:UIAlertControllerStyleAlert];

[alertController addTextFieldWithConfigurationHandler:^(UITextField * _Nonnull textField) {
textField.placeholder = NSLocalizedString(@"+NewName", nil);
}];
// Create the actions.
UIAlertAction *cancelAction = [UIAlertAction actionWithTitle:cancelButtonTitle style:UIAlertActionStyleCancel handler:^(UIAlertAction *action) {
NSLog(@"Cancel");
}];

UIAlertAction *otherAction = [UIAlertAction actionWithTitle:otherButtonTitle style:UIAlertActionStyleDefault handler:^(UIAlertAction *action) {

UITextField *textField = alertController.textFields.firstObject;

NSString *playlistPath = [self dataFilePath:@"playlist.plist"];
if ([[NSFileManager defaultManager]fileExistsAtPath:playlistPath]) {
NSMutableDictionary *playlistDic = [NSMutableDictionary dictionaryWithContentsOfFile:playlistPath];
NSMutableArray *array = [NSMutableArray arrayWithCapacity:0];
if (![[playlistDic allKeys]containsObject:textField.text]) {
[playlistDic setObject:array forKey:textField.text];
}
[playlistDic writeToFile:playlistPath atomically:YES];
if (![playlistArray containsObject:textField.text]) {
[playlistArray insertObject:textField.text atIndex:[playlistArray count]];
}
[[NSUserDefaults standardUserDefaults]setObject:playlistArray forKey:@"playlistArray"];
[self.playlistTableView reloadData];
}
}];
// Add the actions.
[alertController addAction:cancelAction];
[alertController addAction:otherAction];

[self presentViewController:alertController animated:YES completion:nil];
}

结果也OK的。