iOS Question Get UIKeyboardAnimationDurationUserInfoKey and get UIKeyboardAnimationCurveUserInfoKey

Alexander Stolte

Expert
Licensed User
Longtime User
I would like to synchronize the opening of my bottom sheet with a textfield on it, with the opening of the keyboard to create a smoother user experience.
I come across tutorials online that read and work with the following 2 objects:

keyboardAnimationDurationUserInfoKey | Apple Developer Documentation

A user info key to retrieve the duration of the keyboard animation in seconds.
developer.apple.com

keyboardAnimationCurveUserInfoKey | Apple Developer Documentation

A user info key to retrieve the animation curve that the system uses to animate the keyboard onto or off the screen.
developer.apple.com

How can I read out these two properties in B4i?

Thanks
Alex
 
Solution
Ignoring the curve function, at least for now.

Add this objc code to the end of one of the modules:
B4X: 
#if OBJC
@end
@interface B4IViewController (Keyboard2)
@end
@implementation B4IViewController (Keyboard2)
- (void) addWillHide {
     [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(keyboardDidHide:) name:UIKeyboardWillHideNotification object:nil];
}
- (void)keyboardWillShow:(NSNotification *)notification {
    CGSize keyboardSize = [[[notification userInfo] objectForKey:UIKeyboardFrameEndUserInfoKey] CGRectValue].size;
    [self storeDuration:notification];
    [B4IObjectWrapper raiseEvent:self :@"_keyboardstatechanged:" :@[@(keyboardSize.height)]];
}
- (void)storeDuration:(NSNotification*)notification {...
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Erel

B4X founder
Staff member
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Longtime User
Ignoring the curve function, at least for now.

Add this objc code to the end of one of the modules:
B4X: 
#if OBJC
@end
@interface B4IViewController (Keyboard2)
@end
@implementation B4IViewController (Keyboard2)
- (void) addWillHide {
     [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(keyboardDidHide:) name:UIKeyboardWillHideNotification object:nil];
}
- (void)keyboardWillShow:(NSNotification *)notification {
    CGSize keyboardSize = [[[notification userInfo] objectForKey:UIKeyboardFrameEndUserInfoKey] CGRectValue].size;
    [self storeDuration:notification];
    [B4IObjectWrapper raiseEvent:self :@"_keyboardstatechanged:" :@[@(keyboardSize.height)]];
}
- (void)storeDuration:(NSNotification*)notification {
     double duration = ((NSNumber*)[[notification userInfo] objectForKey:UIKeyboardAnimationDurationUserInfoKey]).doubleValue;
    [B4IObjectWrapper getMap:self][@"animation_duration"] = @(duration);
}
- (void)keyboardDidHide:(NSNotification *)notification {
    [self storeDuration:notification];
    [B4IObjectWrapper raiseEvent:self :@"_keyboardstatechanged:" :@[@(0)]];
}
#end if

In B4XPage_Created call this:
B4X: 
#if B4i
    Dim no As NativeObject = B4XPages.GetNativeParent(Me) 'or Page1 in non-B4XPages project.
    no.RunMethod("addWillHide", Null)
#End If
This code also adds the "will hide" event (https://www.b4x.com/android/forum/threads/keyboard-will-hide-notification.126640/#content). Note that the KeyboardStateChanged event will be raised twice when the keyboard closes.

And to get the duration:
B4X: 
Private Sub B4XPage_KeyboardStateChanged (Height As Float)
    Dim ow As NativeObject
    Dim duration As Int = ow.Initialize("B4IObjectWrapper").RunMethod("getMap:", Array(B4XPages.GetNativeParent(Me))) _
        .RunMethod("objectForKey:", Array("animation_duration")).AsNumber * 1000
    Log("duration in ms: " &  duration)
    Log("keyboard state changed: " & Height)
End Sub
 
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Solution

Alexander Stolte

Expert
Licensed User
Longtime User
Thank you very much

Erel said:
Ignoring the curve function, at least for now.
Click to expand...
I have now been able to extend the code and made a tutorial out of it

Animate textfield/panel with the iOS keyboard

This post presents an implementation of animations that animate alongside the iOS keyboard animation. Following the method in this post will allow your views to animate smoothly when the iOS keyboard shows and hides. A big thanks to @Erel who provided code to read the...
www.b4x.com
 
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