blocks|key|837982|text|–+alertView:clickedButtonAtIndex:是UIAlertView的一个委托方法。只需将您在编辑中定义的方法添加到您的控制器实现中，就可以了，因为您已经将控制器设置为AlertView的委托。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|837983|还要添加到你的类头中，以避免任何与委托相关的警告，例如：|837984|@interface+MyViewController+:+UIViewController+<UIAlertViewDelegate>+{
...
};|code-block|syntax|javascript|837985|不要忘记从insert方法中删除[data+addObject:[nameField+text]];和[mainTableView+reloadData];。|837986|entityMap^0|0|X|0|0|0|G|Y|1F|R|0^^$0|@$1|2|3|4|5|6|7|Q|8|@$9|R|A|S|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|T|8|@]|D|@]|E|$]]|$1|H|3|I|5|J|7|U|8|@]|D|@]|E|$K|L]]|$1|M|3|N|5|6|7|V|8|@$9|W|A|X|B|C]|$9|Y|A|Z|B|C]]|D|@]|E|$]]|$1|O|3|-4|5|6|7|10|8|@]|D|@]|E|$]]]|P|$]]

<code>– alertView:clickedButtonAtIndex:</code> is a delegate method of UIAlertView. Just add the method you defined in your edit to your controller implementation and you should be good to go, since you already set the controller to be the AlertView's delegate.

Also add to your class header, to avoid any delegate related warnings, ie:

<pre><code>@interface MyViewController : UIViewController &lt;UIAlertViewDelegate&gt; {
...
};
</code></pre>

Don't forget to remove <code>[data addObject:[nameField text]];</code> and <code>[mainTableView reloadData];</code> from the insert method.

blocks|key|838043|text|人们在使用UIAlertView时经常犯的一个错误是，他们认为向它发送show消息会阻塞主线程。事实并非如此。即使屏幕上有警告，您的代码也会继续执行。因此，您传入的UITextField不存在任何值。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|838044|您需要做的是在UIViewController中实现UIAlertViewDelegate，以获取用户在文本字段中输入的内容。也就是说，您仍然需要检查nil值，因为如果不键入任何内容，则text值将为nil。|838045|更新:这个答案是在苹果开发出通过UIAlertViewStyle向警报添加UITextField的应用程序接口之前发布的。以下是更新后的代码，从@matt借用|838046|UIAlertView+*alert+=+[[UIAlertView+alloc]+initWithTitle:@"Enter+Name"
++++++++++++++++++++++++++++++++++++++++++++++++message:@"++"+++
+++++++++++++++++++++++++++++++++++++++++++++++delegate:self+
++++++++++++++++++++++++++++++++++++++cancelButtonTitle:@"Cancel"
++++++++++++++++++++++++++++++++++++++otherButtonTitles:@"OK",+nil];
alert.alertViewStyle+=+UIAlertViewStylePlainTextInput;
[alert+show];|code-block|syntax|javascript|838047|然后，在UIAlertViewDelegate回调中：|838048|-+(void)alertView:(UIAlertView+*)alertView+clickedButtonAtIndex:(NSInteger)buttonIndex+{
++++if+(buttonIndex+==+1)+{
++++++++NSString+*name+=+[alertView+textFieldAtIndex:0].text;
++++++++//+Insert+whatever+needs+to+be+done+with+"name"
++++}
}|838049|entityMap^0|5|B|Z|4|2A|B|0|7|G|Q|J|23|3|2L|4|2S|3|0|G|G|11|B|0|0|4|J|0|0^^$0|@$1|2|3|4|5|6|7|U|8|@$9|V|A|W|B|C]|$9|X|A|Y|B|C]|$9|Z|A|10|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|11|8|@$9|12|A|13|B|C]|$9|14|A|15|B|C]|$9|16|A|17|B|C]|$9|18|A|19|B|C]|$9|1A|A|1B|B|C]]|D|@]|E|$]]|$1|H|3|I|5|6|7|1C|8|@$9|1D|A|1E|B|C]|$9|1F|A|1G|B|C]]|D|@]|E|$]]|$1|J|3|K|5|L|7|1H|8|@]|D|@]|E|$M|N]]|$1|O|3|P|5|6|7|1I|8|@$9|1J|A|1K|B|C]]|D|@]|E|$]]|$1|Q|3|R|5|L|7|1L|8|@]|D|@]|E|$M|N]]|$1|S|3|-4|5|6|7|1M|8|@]|D|@]|E|$]]]|T|$]]

A common mistake that people make when using a <code>UIAlertView</code> is that they think that sending it a <code>show</code> message will block the main thread. It does not. Your code continues to execute, even though there is an alert on the screen. Thus, no value exists for the <code>UITextField</code> that you have passed in.

What you need to do is implement the <code>UIAlertViewDelegate</code> in your <code>UIViewController</code> to grab whatever a user has entered into the text field. That said, you still have to check for a <code>nil</code> value, because if you don't type anything in, the <code>text</code> value will be <code>nil</code>.

UPDATE: This answer was posted before Apple created an API for adding a <code>UITextField</code> to an alert through the <code>UIAlertViewStyle</code>. Here is the updated code, borrowed from @matt

<pre><code>UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Enter Name"
 message:@" " 
 delegate:self 
 cancelButtonTitle:@"Cancel"
 otherButtonTitles:@"OK", nil];
alert.alertViewStyle = UIAlertViewStylePlainTextInput;
[alert show];
</code></pre>

Then, in the <code>UIAlertViewDelegate</code> call back:

<pre><code>- (void)alertView:(UIAlertView *)alertView clickedButtonAtIndex:(NSInteger)buttonIndex {
 if (buttonIndex == 1) {
 NSString *name = [alertView textFieldAtIndex:0].text;
 // Insert whatever needs to be done with "name"
 }
}
</code></pre>

blocks|key|1052796|text|UIAlertView+*myAlert+=+[[UIAlertView+alloc]+initWithTitle:@"Alert+title"+
++++++++++++++++++++++++++++++++++++++++++++++++++message:@"alert+message"+
+++++++++++++++++++++++++++++++++++++++++++++++++delegate:self+
++++++++++++++++++++++++++++++++++++++++cancelButtonTitle:@"Cancel"+
++++++++++++++++++++++++++++++++++++++++otherButtonTitles:@"Ok",+nil];
[myAlert+addTextFieldWithValue:nil+label:@"<place+holder>"];
[[myAlert+textField]+setTextAlignment:UITextAlignmentCenter];
[[myAlert+textField]+becomeFirstResponder];
[myAlert+show];
[myAlert+release];
myAlert+=+nil;+++++++++++++++|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|1052797|不需要添加自定义文本字段。您可以使用addTextFieldWithValue方法直接添加。|unstyled|1052798|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$B|C]]|$1|D|3|E|5|F|7|J|8|@]|9|@]|A|$]]|$1|G|3|-4|5|F|7|K|8|@]|9|@]|A|$]]]|H|$]]

<pre><code>UIAlertView *myAlert = [[UIAlertView alloc] initWithTitle:@"Alert title" 
 message:@"alert message" 
 delegate:self 
 cancelButtonTitle:@"Cancel" 
 otherButtonTitles:@"Ok", nil];
[myAlert addTextFieldWithValue:nil label:@"&lt;place holder&gt;"];
[[myAlert textField] setTextAlignment:UITextAlignmentCenter];
[[myAlert textField] becomeFirstResponder];
[myAlert show];
[myAlert release];
myAlert = nil; 
</code></pre>

No need to add a custom textfield. You can directly add using addTextFieldWithValue method.

blocks|key|838114|text|您不需要将自己的文本字段添加到AlertView中，而是设置适当的样式|type|unstyled|depth|inlineStyleRanges|entityRanges|data|838115|UIAlertView+*alert+=+[[UIAlertView+alloc]+initWithTitle:@"Enter+Name"
++++++++++++++++++++++++++++++++++++++++++++++++message:@"++"+++
+++++++++++++++++++++++++++++++++++++++++++++++delegate:self+
++++++++++++++++++++++++++++++++++++++cancelButtonTitle:@"Cancel"
++++++++++++++++++++++++++++++++++++++otherButtonTitles:@"OK",+nil];
alert.alertViewStyle+=+UIAlertViewStylePlainTextInput;
[alert+show];|code-block|syntax|javascript|838116|然后在按下OK+(按钮1)后访问输入的文本|838117|-+(void)alertView:(UIAlertView+*)alertView+clickedButtonAtIndex:(NSInteger)buttonIndex
{
++++if+(buttonIndex+==+1)+{
++++++++NSString+*name+=+[alertView+textFieldAtIndex:0].text;
++++++++//+name+contains+the+entered+value
++++}
}|838118|entityMap^0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|N|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|O|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|P|8|@]|9|@]|A|$E|F]]|$1|K|3|-4|5|6|7|Q|8|@]|9|@]|A|$]]]|L|$]]

You don't need to add your own text field to the AlertView but instead set the appropriate style

<pre><code>UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Enter Name"
 message:@" " 
 delegate:self 
 cancelButtonTitle:@"Cancel"
 otherButtonTitles:@"OK", nil];
alert.alertViewStyle = UIAlertViewStylePlainTextInput;
[alert show];
</code></pre>

Then access the entered text after OK (button 1) was pressed

<pre><code>- (void)alertView:(UIAlertView *)alertView clickedButtonAtIndex:(NSInteger)buttonIndex
{
 if (buttonIndex == 1) {
 NSString *name = [alertView textFieldAtIndex:0].text;
 // name contains the entered value
 }
}
</code></pre>

I'm trying to get text from an alert view and add it to my mutable array to list in a table view. I realize there is a similar question that was posted a few months ago, but I dont understand how to utilize the given answer. 

<pre><code>-(IBAction)insert {
 UIAlertView* dialog = [[UIAlertView alloc] init];
 [dialog setDelegate:self];
 [dialog setTitle:@"Enter Name"];
 [dialog setMessage:@" "];
 [dialog addButtonWithTitle:@"Cancel"];
 [dialog addButtonWithTitle:@"OK"];

 UITextField *nameField = [[UITextField alloc] initWithFrame:CGRectMake(20.0, 45.0, 245.0, 25.0)];
 [nameField setBackgroundColor:[UIColor whiteColor]];
 [dialog addSubview:nameField];
 [dialog show];

 [data addObject:[nameField text]];
 [mainTableView reloadData];
</code></pre>

However my app crashes because it says I'm attempting to insert a nil object at index 0. What am I doing wrong?

EDIT: Ok I think I'm missing a method to handle the alertview. So I found this:

<pre><code>- (void)alertView:(UIAlertView *)alertView clickedButtonAtIndex:(NSInteger)buttonIndex {
 NSString *buttonTitle=[alertView buttonTitleAtIndex:buttonIndex];
 if([buttonTitle isEqualToString:@"Cancel"]) {
 return;
 }
 else if([buttonTitle isEqualToString:@"Ok"]) {
 [data addObject:nameField.text];

 }
</code></pre>

Now I just need to connect the pieces, but not sure how.

Getting text from UIAlertView

我正在尝试从一个警报视图中获取文本，并将其添加到我的可变数组中，以便在表视图中列出。我意识到几个月前发布了一个类似的问题，但我不明白如何利用给定的答案。-(IBAction)insert {    UIAlertView* dialog = [[UIAlertView alloc] init];    [dialog ...

问从UIAlertView获取文本
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