[Bug] Label MaxLines property has a different behaviour on Android and iOS

[cliffconclusion]

Description

When a label is set to MaxLines 0, on iOS it will show maximum available lines, on Android it shows literally 0 lines. I would expect the iOS behaviour.

Our situation:
We have a label which is set to 2 lines maximum when we load the screen. When the user presses the label it is supposed to extend and show the full text. We tried doing this by setting MaxLines to 0. this works on iOS, but does not work on Android.

Steps to Reproduce

1. Create a Label.
2. Put in a text with multiple lines.
3. Set MaxLines to 0.

Expected Behavior

Setting the MaxLines to 0 shows all the lines available. (if I would want to show 0 lines, I could just set the IsVisible to false)

Actual Behavior

On iOS => Expected behaviour.
On Android => The label literally shows 0 lines.

Basic Information

• Version with issue: Xamarin.Forms 4.7.0.1080
• Last known good version: -
• IDE: Visual Studio For Mac 8.6.5 (build 23)
• Platform Target Frameworks:
  • iOS: iOS 11
  • Android: Android 9.0
• Nuget Packages: Xamarin Essentials, Xamarin Forms
• Affected Devices: As far as we know all of them.

Workaround

We currently work around it by setting the MaxLines to a ridiculously high number. Which will make sure in every case it shows the maximum lines available.

[jsuarezruiz]

I have created a repro sample:

Issue11427.zip

In Android with MaxLines = 0:

In iOS:

[alirazamsp]

I am having the same issue on Android with Xamarin Forms 4.8 version. Is there any workaround for this bug ?

[viveknegi51288]

@samhouts I also have the same issue. Maxline is not working propely in Xamarin 4.8..

I need to set Maxline from Viewmodel (using prism) but its not reflecting the size in the android and ios\

Please provide a sample app

[nwilliams]

I would actually argue that iOS is exhibiting the unexpected behavior here. If you set MaxLines back to its default value of -1, all lines are displayed for the Label for both platforms. Setting MaxLines to 0 lets you collapse a Label entirely (for Android, at least).

If this is changed for Android it could actually end up breaking layouts for some people, since labels still take up space with IsVisible set to false.