CODEWITHSUNDEEP
iosuistackviewios-autolayout
Ryan
Ryan

Reputation: 4884

height of UISlider in a horizontal UIStackView

The arranged subviews in UIStackView with a horizontal axis must have the same height with the UIStackView's height. However it is not true for a UISlider. Whatever height I set for UIStackView, the height of UISlider in the stack view will have 1px taller height.

enter image description here

I set UIStackView's height as 40 and didn't set any auto layout for the UISlider.

enter image description here

But the height of UISlider is 41 which I expected 40.

Is there any reason for this? and any way to fix this issue?

Upvotes: 0

Views: 241

Answers (1)

DonMag
DonMag

Reputation: 77462

UISlider seems to do some odd stuff with its sizing.

Ignoring the stack view for the moment, if you simply apply width and height constraints to a UISlider, they won't match the actual width and height at run-time. You get an extra 4-pts width and an extra 1-pt height.

However...

If you constrain another view relative to the slider, the other view respects the slider's constraints, not the slider's rendered size.

Take a look at this image-capture from Debug View Hierarchy:

enter image description here

  • Slider has
    • width = 100
    • height = 40

but the orange rect (the slider background) is actually 104 x 41 - and that's what you'll get if you print(mySlider.frame) at run-time.

  • Left Label has

    • trailing = slider.leading
    • height = slider.height
    • centerY = slider.centerY

  • Right Label has

    • leading = slider.trailing
    • height = slider.height
    • centerY = slider.centerY

Both label heights are exactly 40-pts - which matches the constraint.

Note also that the label frames overlap the slider background by 2-pts, showing that the label x-positioning is, again, matching the constraints, not the rendered slider view frame.

If you inspect the views when the slider is embedded in a UIStackView, you will see (well, you have seen) that the frame size is greater than the stack view's frame. But, the slider's frame will extend outside the actual frame of the stack view... the stack view (and its other arranged subviews) will continue to respect the constraints you've given it.

All of which is to say... if the "size mismatch" is not causing any issues, I wouldn't worry about it.

Upvotes: 2

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