setting trailing edge to inset has opposite of expected (and previous) behavior

[colinta]

New Issue Checklist

• I have looked at the Documentation
• I have read the F.A.Q.

Issue Info

Info	Value
Platform	ios
Platform Version	10.0
SnapKit Version	3.0.0
Integration Method	cocoapods

Issue Description

This might be because

UIEdgeInsets are now have their right and bottom value inverted
(PS "are now have")

But the example that immediately follows that warning uses all positive values make.edges.equalTo(UIEdgeInsets(top: 10, left: 10, bottom: 10, right: 10)).inset(), which leads me to believe that I should continue to use positive values. Plus that makes sense, given that UIEdgeInsets use positive values to make rects smaller than their enclosing rect.

So given all that - should I be using negative values here? I hope that's not the case, I am re-using this UIEdgeInset in other calculations in my app, which all assume that positive values make the rect smaller.

[robertjpayne]

@colinta for edges (left/right/top/bottom) UIEdgeInsets now behave as you described, this is a change from 0.22.0 and earlier in which the right/bottom were not inverted so you had to pass negative values.

Are you saying when doing like: make.leading.trailing.top.bottom.equalTo(UIEdgeInsets) it's not resulting in the same expected behaviour?

[colinta]

Interesting, so it sounds like they're supposed to work how I would expect. I just updated an app to use SnapKit 3, and one of my views was placed incorrectly. Here's the relevant code:

class MainScreen: UIView {
    struct Size: {
        static let tableMargins = UIEdgeInsets(top: 90, left: 20, bottom: 45, right: 20)
    }

        table.snp.makeConstraints { make in
            make.top.leading.trailing.equalTo(overlay).inset(Size.tableMargins)

What I expected (and this was the case in 0.22) was for the left and right edges to be 20pt from the overlay edges. Instead, the left side is placed correctly, but the right is not (it's 20pt off-screen).

I haven't tried the usage equalTo(insets).inset(), but in my case table is not a direct subview of overlay, so I'm not sure I can use that anyway.

[robertjpayne]

@colinta the issue is probably leading/trailing are broken as a regression!

[colinta]

Ok, I'll see if I can help! I'll take a look at ConstraintConstantTarget.swift. At first glance, I noticed this:

if let value = self as? ConstraintInsets
...
    switch layoutAttribute {
    ...
    case .right, .rightMargin:
        return -value.right
    case .trailing, .trailingMargin:
        return (ConstraintConfig.interfaceLayoutDirection == .leftToRight) ?
            value.right :
            -value.left
    }
}

I see that .right uses -value.right, but .trailing uses value.right.

[robertjpayne]

@colinta yea so this is tricky… It should probably be inverted for both if trailing edge?

[robertjpayne]

e.g. UIEdgeInsets(left: 10, right: 10) in both cases the constant for the right edge should be -10

[robertjpayne]

@colinta should be fixed in 3.0.1 release that just went out. Let me know if it persists!

[colinta]

Verified working! Thanks, Robert.