UIAlertView的自动消失，手动消失和自定制消失

UIAlertView的消失本质其实是触发了一个dismiss事件。

触发这个事件有以下两种方法：

1.按钮点击，UIAlertView上如果有按钮，点击任何按钮都会触发该事件，UIAlertView消失；

2.代码模拟点击

 [AlertObject dismissWithClickedButtonIndex:0 animated:NO]

1。创建一个自动消失的UIAlertView，这种消失方法的本质其实就是：使用定时器+代码模拟点击

 -(void) performDismiss:(NSTimer *)timer
 {
 [Alert dismissWithClickedButtonIndex:0 animated:NO];
 [Alert release];
 }

 -(void)presentAlert
 {
 Alert = [[UIAlertView alloc] initWithTitle:@"警告" message:@"出错啦！" delegate:self cancelButtonTitle:nil otherButtonTitles:nil, nil];

 [NSTimer scheduledTimerWithTimeInterval:2.0f target:self selector:@selector(performDismiss:) userInfo:nil repeats:NO];
 [Alert show];
 }

2.手动消失

如果你的UIAlertView上有按钮的话，点击任何一个按钮，都会触发一个dismiss事件，引起UIAlertView的消失。

3.自定制的消失，其实就是在自己认为合适的时候模拟点击。

下面这个例子是在textField的delegate执行即点击returnKey且输入昵称合法的时候，UIAlertView消失。

 - (void) enterNickName:(NSString*)msg
 {
 prompt = [[UIAlertViewalloc] initWithTitle:@"设置昵称"
 message:msg
 delegate:self
 cancelButtonTitle:nil
 otherButtonTitles:nil];

 UITextField *textField = [[UITextFieldalloc] initWithFrame:CGRectMake(27.0,70.0, 230.0, 30.0)];
 [textField setBackgroundColor:[UIColorwhiteColor]];
 [textField setPlaceholder:@"输入昵称"];
 textField.layer.cornerRadius=6.0;
 textField.delegate=self;
 textField.contentVerticalAlignment=UIControlContentVerticalAlignmentCenter;
 [prompt addSubview:textField];
 [textField becomeFirstResponder];
 textField.keyboardType=UIKeyboardTypeDefault;
 textField.keyboardAppearance=UIKeyboardAppearanceDefault;
 textField.returnKeyType=UIReturnKeyDone;
 [textField release];
 [promptsetTransform:CGAffineTransformMakeTranslation(0.0, -40.0)]; //可以调整弹出框在屏幕上的位置
 [prompt show];
 }

 #pragma textField delegate
 - (BOOL)textFieldShouldReturn:(UITextField *)textField
 {
 NSLog(@"nickname=%@",textField.text);
 if (nil==textField.text ||0==[[textField.textstringByTrimmingCharactersInSet:[NSCharacterSetwhitespaceCharacterSet]] length])
 {
 prompt.message=@"\n\n昵称不能为空!";
 return YES;
 }
 if ([[textField.textstringByTrimmingCharactersInSet:[NSCharacterSetwhitespaceCharacterSet]] length]<2
 ||[[textField.textstringByTrimmingCharactersInSet:[NSCharacterSetwhitespaceCharacterSet]] length]>15)
 {
 prompt.message=@"\n\n昵称只支持2-15个字，请重新设置";
 return YES;
 }
 [prompt dismissWithClickedButtonIndex:0animated:NO];//触发dismiss
 [prompt release];
 }