sampettersson / placement

Layout protocol & ViewThatFits backport for iOS 14-15

Hi there 👋

placement's Issues

1.5.0 makes different layout behavior against 1.4.1

first of all, I appreciate your wondrous works.
I've made a small library that lays elements out in flow.

https://github.com/FluidGroup/swiftui-WrapLayout

Then I noticed the latest version 1.5.0 that runs something different against 1.4.1.
Actually, laying out does not work correctly.

For now, it's still just head up for you. I will investigate more about what's going on inside.

iOS 15.x

1.4.1

1.5.0 - all viewers are placed in same position.

makeCache is not called again when Layout should be invalidated from parameters.

Example:
Given we have a parameter columnCount that we pass into a PlacementLayout through init(columnCount: Int), I would expect the layout to invalidate and call makeCache(subviews:) so that a cache can be made taking new parameters into consideration. Layout has this behavior but PlacementLayout does not.

Sample:

AutoflowDenseGridPlacementLayout(columnCount: columnCount) {
    ForEach(Array(items.enumerated()), id: \.element) { index, item in
        ZStack {
            Color.red
            Text("\(index)")
                .foregroundColor(.white)
        }
        .placementLayoutValue(key: PAutoflowGridItemSizeValueKey.self, value: item.size)
    }
  }
  .padding(16)

Incorrect (PlacementLayout)

PlacementLayout_Incorrect.mp4

Correct (Layout):

Layout_Correct.mp4

Incorrect Defaults

replacingUnspecifiedDimensions(by:)

A default parameter exists for replacingUnspecifiedDimensions(by:) that is not in Placement.

updateCache(_:subviews:)

The default implementation of updateCache(_ cache: subviews:) should call makeCache.

Both issues are fixed in this PR

.placementLayoutValue(key: value:) does not function properly on iOS 16 with prefersLayoutProtocol set to false.

placementLayoutValue(key: value) does not get propagated properly to PlacementLayoutSubview on iOS 16 when prefersLayoutProtocol is set to false.

It seems the logic is set up to always use layoutValue(key: value) when on iOS 16. But the retrieval of these values doesn't seem to be pulled from the same location when attached to PlacementLayoutSubview.

Documentation is inaccessible

I was just investigating this library, but I am unable to access the documentation.