键盘出现时如何在可见框中心移动视图？

Question

I have a standard UIView (containing an image view, two textfield and a button) embedded in a root scroll view. I'm using AutoLayout to put the UIView at the center of the scroll view, like is shown in the screenshot below.

I am trying to write a method that moves up the UIView when the keyboard appears, so that this view will appear at the center of the smaller visible frame. To achieve this, I calculated some heights.

- (void)keyboardWillShow:(NSNotification *)notification {
    // Determines the size of the keyboard frame
    CGSize keyboardSize = [[[notification userInfo] objectForKey:UIKeyboardFrameBeginUserInfoKey] CGRectValue].size;

    [UIView animateWithDuration:0.3 animations:^{
        // Gets the root 'UIView' frame and stores it in a variable
        CGRect viewFrame = self.itemsView.frame;
        // This is the height of the visible frame once the keyboard appears
        double visibleFrameHeight = (self.view.frame.size.height - keyboardSize.height);
        // How much the 'UIView' should move up
        double offset = ((visibleFrameHeight - viewFrame.size.height / 2);
        // Moves up the 'UIView'
        viewFrame.origin.y = -offset;
        self.itemsView.frame = viewFrame;
    }];
}

The problem is that the UIView is moved too up, like shown below.

Why is this happening and how can I fix it?

Answer 1

If your view is already embedded in a UIScrollView then you can just adjust the scrollview's contentOffset to move the view (then you get the animation for free).

Assuming the scrollview is available on an outlet called scrollView , and that you want to keep the view centered, you could just shift the content offset by 1/2 the keyboard height. Also - probably safer to use the UIKeyboardFrameEndUserInfoKey to get the final frame of the keyboard:

- (void)keyboardWillShow:(NSNotification *)notification {
    // Determines the size of the keyboard frame
    CGSize keyboardSize = [[[notification userInfo] objectForKey:UIKeyboardFrameEndUserInfoKey] CGRectValue].size;
    self.scrollView.contentOffset = CGPointMake(0, keyboardSize.height / 2);
}

- (void)keyboardWillHide:(NSNotification *)notification {
    self.scrollView.contentOffset = CGPointZero;
}

Answer 2

you have to set one IBOutlet for UIScrollView in .h file like this: IBOutlet UIScrollView *scrLogin;

then after in Your xib file set delegate for UIScrollview and all UiTextfield.

then after set this code in your .m file

You have set all design like UIimageview, UItextfield, & UIButton & every thing in UIScrollView.

- (void)viewDidLoad {
          [scrLogin setContentSize:CGSizeMake(320, 790)];
          [scrLogin setContentOffset:CGPointMake(0, 0) animated:YES];
    }
 #pragma mark - Textfield Delegate
 - (BOOL)textFieldShouldReturn:(UITextField *)textField {
                if (textField==txtUserName) {
                    [txtUserName resignFirstResponder];
                    [txtPsw becomeFirstResponder];
                }else{
                    [txtPsw resignFirstResponder];
                    [scrLogin setContentOffset:CGPointMake(0, -60) animated:NO];
                    //[self btnLoginTapped:self];
                }
                return YES;
            }
- (void)textFieldDidBeginEditing:(UITextField *)textField{
  if(textField==txtUserName){
        if (IS_IPHONE_4s) {
           [scrLogin setContentOffset:CGPointMake(0, 20) animated:true];
        }else{
           [scrLogin setContentOffset:CGPointMake(0, 0) animated:true];
        }
 }else if(textField==txtPsw){
    [scrLogin setContentOffset:CGPointMake(0, 40) animated:true];
 }

}

I hope it's help you. if you have any problem then tell me.

Answer 3

我建议使用https://github.com/hackiftekhar/IQKeyboardManager ，它易于使用并且可在您的整个应用程序中使用（无需再次手动计算键盘高度）