Keyboard 位置变化

#ifdef __IPHONE_5_0
    float version = [[[UIDevice currentDevice] systemVersion] floatValue];
    if (version >= 5.0) {
        [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(keyboardWillShow:) name:UIKeyboardWillChangeFrameNotification object:nil];
    }
#endif

5.0后版本可以使用

#pragma mark -
#pragma mark Responding to keyboard events
- (void)keyboardWillShow:(NSNotification *)notification {
    
    /*
     Reduce the size of the text view so that it's not obscured by the keyboard.
     Animate the resize so that it's in sync with the appearance of the keyboard.
     */
    
    NSDictionary *userInfo = [notification userInfo];
    
    // Get the origin of the keyboard when it's displayed.
    NSValue* aValue = [userInfo objectForKey:UIKeyboardFrameEndUserInfoKey];
    
    // Get the top of the keyboard as the y coordinate of its origin in self's view's coordinate system. The bottom of the text view's frame should align with the top of the keyboard's final position.
    CGRect keyboardRect = [aValue CGRectValue];
    
    if( keyboardRect.size.height <= 216 )
    {
        _CommentPostView.frame  =  CGRectMake(0, 505-216-46, 320, 46);
    }
    else
    {
        _CommentPostView.frame  =  CGRectMake(0, 505-252-46, 320, 46);
    }
}
#pragma mark UITextField delegate end---------------------