AutoLayout works in ios 8 but not in ios 7?

Question

I am using autolayout within a UICollectionViewCell. Super simple layout: just a UILabel. I want the UILabel to take up the full width minus a 20 px inset and be centered in the cell both vertically and horizontally. I have set up constraints that do just that. If i run it on any ios 8 device or simulator it works perfectly. However, when I run it on some ios 7 devices the constraints have no effect. I tried looking through the apple docs, but none of their changes seems to be around auto layout.

Here's the XML source code though I doubt it means much:

<constraints>
            <constraint firstItem="OIc-cg-9hO" firstAttribute="leading" secondItem="Ga6-nx-lOn" secondAttribute="leading" constant="20" id="A7U-sd-fcL"/>
            <constraint firstAttribute="centerY" secondItem="OIc-cg-9hO" secondAttribute="centerY" id="G9e-9W-aDS"/>
            <constraint firstAttribute="centerX" secondItem="OIc-cg-9hO" secondAttribute="centerX" id="TrB-hI-7Kw"/>
            <constraint firstAttribute="trailing" secondItem="OIc-cg-9hO" secondAttribute="trailing" constant="20" id="yjH-nf-D9U"/>
        </constraints>

More of a workaround than an answer: but I added the constraints in code as follows:

    [self addConstraint:[NSLayoutConstraint constraintWithItem:self.cellName
                                                      attribute:NSLayoutAttributeWidth
                                                      relatedBy:NSLayoutRelationEqual
                                                         toItem:self
                                                      attribute:NSLayoutAttributeWidth
                                                     multiplier:1.0
                                                       constant:-20.0]];

[self addConstraint:[NSLayoutConstraint constraintWithItem:self.cellName
                                                      attribute:NSLayoutAttributeCenterX
                                                      relatedBy:NSLayoutRelationEqual
                                                         toItem:self
                                                      attribute:NSLayoutAttributeCenterX
                                                     multiplier:1.0
                                                       constant:0.0]];

[self addConstraint:[NSLayoutConstraint constraintWithItem:self.cellName
                                                      attribute:NSLayoutAttributeCenterY
                                                      relatedBy:NSLayoutRelationEqual
                                                         toItem:self
                                                      attribute:NSLayoutAttributeCenterY
                                                     multiplier:1.0
                                                       constant:0.0]];

In order for it to work I needed both the coded constraints and the IB constraints. Dunno Why!

What result do you get in iOS 7? I don't see anything in those constraints that shouldn't work in in iOS 7. — rdelmar, Oct 03 '14 at 01:02
Placing the constraints in code in the layoutsubviews was the only way to make it work. You get some complaints about overlapping constraints, but it works. — user3534641, Oct 06 '14 at 21:32
Could you be using different screen sizes for iOS 7 vs 8? Some of your constraints might not be installed for some size classes. — TotoroTotoro, Oct 07 '14 at 20:36
Nope iPhone 5s in ios 7 and iPhone 5s in ios8 same with iPad Mini (have tried all simulators as well). — user3534641, Oct 08 '14 at 00:01

score 5 · Answer 1 · edited May 23 '17 at 10:28

5

It sounds like your Interface Builder constraints are using the "Constraint to Margin" option which is not supported on iOS7. Open the constraints in IB and check if any of them have items with the 'relative to margin' option checked.

See What is "Constrain to margin" in Storyboard in Xcode 6 and What is "Constrain to margin" in Storyboard in Xcode 6 for more details on constraint to margin.

edited May 23 '17 at 10:28

Community

1
1

answered Oct 13 '14 at 08:13

pposthoorn

61
5

1

I can't even find that option but there's nothing in the xml – user3534641 Oct 17 '14 at 01:30

score 4 · Answer 2 · answered Jan 27 '15 at 16:46

This happened to me, you have to check every constraint in the UI and remove the Relative to Margin which was introduced with iOS 8 and doesn't support iOS 7, don't forget those inside some places where you might forget (like UITableView cells).

To find this option:

Tap on the UI control
Go to the Size Inspector
Double click any constraint and check the margin thing, just turn it off and fix your constraint if anything changes.

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AutoLayout works in ios 8 but not in ios 7?

2 Answers2