ios - Why these layout issues occur when debugging view hierarchy while the UI layout in simulator is OK -


i use visual format layout subviews in cell this:

contentview.addsubview(accountlabel) contentview.addsubview(contentlabel) contentview.addsubview(timelabel)  let views: [string : any] = [     "accountlabel": accountlabel,     "contentlabel": contentlabel,     "timelabel": timelabel ]  let hconstraint1 = nslayoutconstraint.constraints(withvisualformat: "h:|-15-[accountlabel]-[timelabel]-8-|", options: [.alignallcentery], metrics: nil, views: views) let hconstraint2 = nslayoutconstraint.constraints(withvisualformat: "h:[contentlabel]-8-|", options: [], metrics: nil, views: views) let vconstraint = nslayoutconstraint.constraints(withvisualformat: "v:|-12-[accountlabel]-8-[contentlabel]-12-|", options: [.alignallleading], metrics: nil, views: views) nslayoutconstraint.activate(hconstraint1+hconstraint2+vconstraint)

and looks ok when run in simulator:

enter image description here

however, layout issues occur when debugging view hierarchy:

enter image description here

why these layout issues occur while runtime ui looks ok?

is wrong visual format string above? or it's bug of xcode?

how remove these layout issues?

well, i'm not expert constraints, see 1 "correctable" issue , 1 "that's weird maybe it's bug" issue.

as understand it, auto-layout try satisfy constraints -- even if ambiguous. if fails, see error message in console, along lines of "will attempt satisfy breaking..."

so warning information see in debug view hierarchy more informational "fix error" directive.

that said...

you have accountlabel , timelabel constrained relative each other, both have same compression resistance. so, long amount of text in each label "fit", ok.

but suppose accountlabel gets text string of "this user name long fit here"?

should (i use background colors see frames):

enter image description here

or this:

enter image description here

that's why horizontal position , width showing "ambiguous".

you can fix issue adding 1 line. assuming want accountlabel truncated:

    accountlabel.setcontentcompressionresistancepriority(749, for: .horizontal)

will trick. default 750, line tells auto-layout give timelabel higher resistance.

the height , vertical positions showing ambiguous don't seem right. don't see wrong constraints.

if use same font 3 labels? no ambiguous warnings.

if use different font size timelabel (as show in images), there are warnings in debug view hierarchy.

except... if scroll cells reused? warnings have gone away!

edit: op states in comment, vertical ambiguity can eliminated (prior scrolling) giving different content hugging priority values accountlabel , contentlabel.

since default hugging priority 250:

    accountlabel.setcontenthuggingpriority(249, for: .vertical)

clears warning.

i'm not convinced it's necessary... does appear job.


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