KeyboardSizedView

KeyboardSizedView.m

// 
// Rewrited from Swift to obj-c
// Original source: https://github.com/objcio/app-architecture/blob/master/One-App-Eight-Architectures/MultiPattern/KeyboardSizedView.swift
//

@interface KeyboardSizedView ()

@property (nonatomic, strong) NSLayoutConstraint *keyboardConstraint;

@end

@implementation KeyboardSizedView

-(void)didMoveToSuperview
{
    [super didMoveToSuperview];

    if (self.superview == nil)
    {
        [NSNotificationCenter.defaultCenter removeObserver:self];

        return;
    }
    [NSNotificationCenter.defaultCenter addObserver:self
                                           selector:@selector(keyboardChanged:)
                                               name:UIKeyboardWillShowNotification
                                             object:nil];
    [NSNotificationCenter.defaultCenter addObserver:self
                                           selector:@selector(keyboardChanged:)
                                               name:UIKeyboardWillHideNotification
                                             object:nil];
    self.backgroundColor = UIColor.clearColor; // to be sure the backgroundColor isn't default(white)
}


#pragma mark - Notification handling

-(void)keyboardChanged:(NSNotification *)notification
{
    NSDictionary *userInfo = notification.userInfo;
    NSTimeInterval animationDuration = ((NSNumber *)userInfo[UIKeyboardAnimationDurationUserInfoKey]).doubleValue;
    UIViewAnimationCurve animationCurve = ((NSNumber *)userInfo[UIKeyboardAnimationCurveUserInfoKey]).intValue;

    CGRect rect = CGRectZero;
    if (notification.name == UIKeyboardWillShowNotification)
    {
        rect = [self convertRect:((NSValue *)userInfo[UIKeyboardFrameEndUserInfoKey]).CGRectValue
                        fromView:nil];
        rect.size.height -= (rect.origin.y + rect.size.height);
    }
    self.keyboardConstraint.constant = fmax(0., rect.size.height);

    [UIView animateWithDuration:animationDuration
                          delay:0.
                        options:((animationCurve << 16) | UIViewAnimationOptionLayoutSubviews)
                     animations:^
     {
         [self layoutIfNeeded];
     }
                     completion:nil];
}


#pragma mark - Lazy load

-(NSLayoutConstraint *)keyboardConstraint
{
    if (_keyboardConstraint)
    {
        return _keyboardConstraint;
    }
    _keyboardConstraint = [self.heightAnchor constraintEqualToConstant:0.];
    _keyboardConstraint.active = true;

    return _keyboardConstraint;
}


@end