UITextField控件处理键盘弹出时遮住输入框的问题

原文连接： 
http://www.devdiv.com/thread-70159-1-1.html

实现以下三个方法，如果弹出的键盘会遮住输入框 ，整体的界面会向上移动，这样就不会遮住输入框了。自己增加UITextFieldDelegate委托。 
只适合iPhone,如果想要支持iPad,只要把216改成iPad上面键盘的高度即可。

 - (void)keyboardWillShow:(NSNotification *)noti
 {
         //键盘输入的界面调整
         //键盘的高度
         float height = 216.0;
         CGRect frame = self.view.frame;
         frame.size = CGSizeMake(frame.size.width, frame.size.height - height);
         [UIView beginAnimations:@"Curl"context:nil];//动画开始
         [UIView setAnimationDuration:0.30];
         [UIView setAnimationDelegate:self];
         [self.view setFrame:frame];
         [UIView commitAnimations];
 }

 - (BOOL)textFieldShouldReturn:(UITextField *)textField
 {
     // When the user presses return, take focus away from the text field so that the keyboard is dismissed.
     NSTimeInterval animationDuration = 0.30f;
     [UIView beginAnimations:@"ResizeForKeyboard" context:nil];
     [UIView setAnimationDuration:animationDuration];
     CGRect rect = CGRectMake(0.0f, 0.0f, self.view.frame.size.width, self.view.frame.size.height);
     self.view.frame = rect;
     [UIView commitAnimations];
     [textField resignFirstResponder];
     return YES;
 }

 - (void)textFieldDidBeginEditing:(UITextField *)textField
 {
         CGRect frame = textField.frame;
         int offset = frame.origin.y +  - (self.view.frame.size.height - 216.0);//键盘高度216
         NSTimeInterval animationDuration = 0.30f;
         [UIView beginAnimations:@"ResizeForKeyBoard" context:nil];
         [UIView setAnimationDuration:animationDuration];
         float width = self.view.frame.size.width;
         float height = self.view.frame.size.height;
         if(offset > )
         {
                 CGRect rect = CGRectMake(0.0f, -offset,width,height);
                 self.view.frame = rect;
         }
         [UIView commitAnimations];
 }

另外我自己做了一点修改： 
在实际用的时候，键盘消失原来的控件并没有回归都原来的位置，而是上移了20个像素，我估计是因为顶部Bar的原因，只要将22行代码改成如下就可以了： 
CGRect rect = CGRectMake(0.0f, 20.0f, self.view.frame.size.width, self.view.frame.size.height);