CODEWITHSUNDEEP
iosxcodemacosstoryboard
kelin
kelin

Reputation: 11991

Is it possible to copy constraints from one view to another?

Suppose I use Interface Builder to create UI in Storyboard with Auto Layout. Can I copy or move some constraints from one view to another?

Upvotes: 36

Views: 34125

Answers (3)

Iulian Onofrei
Iulian Onofrei

Reputation: 9740

You can if you understand and learn how the XML of the .xib files works. I got pretty used to them and so I was able to move a view with its constraints into another view.

I'll try to explain it step by step:

  1. Create an outlet for it: myView
  2. Right click the .xib file > Open As > Source Code or open it in another editor (e.g. Sublime Text)

  3. Search myView and you'll find something like:

    <outlet property="myView" destination="i5M-Pr-FkT" id="sfx-zR-JGt"/>

    and copy the destination attribute's value

  4. Search the copied id (i5M-Pr-FkT) and one of the results will be a view tag:

    <view contentMode="scaleToFill" id="i5M-Pr-FkT"> <!-- 1 -->
    ...
</view>

  5. Cut and paste this whole view tag in the needed view's subviews tag:

    <view contentMode="scaleToFill" id="Ovp-8Y-qHZ"> <!-- 2 -->
    <subviews>
        <view contentMode="scaleToFill" id="i5M-Pr-FkT"> <!-- 1 -->
            ...
        </view>
    </subviews>
</view>

  6. Continue searching for the copied id and you'll find some constraints that have it like:

    <constraint firstItem="w7M-JQ-JWD" firstAttribute="leading" secondItem="i5M-Pr-FkT" secondAttribute="leading" id="EwH-B1-XWY"/>

  7. You need to move this into the constraints tag of the lowest common ancestor of both superviews (the old one and the new one):

    <view contentMode="scaleToFill" id="rK2-sE-P0d"> <!-- 3 -->
    <subviews>
        <view contentMode="scaleToFill" id="Ovp-8Y-qHZ"> <!-- 2 -->
            <subviews>
                <view contentMode="scaleToFill" id="i5M-Pr-FkT"> <!-- 1 -->
                    ...
                </view>
            </subviews>
        </view>
    </subviews>
    <constraints>
        <constraint firstItem="w7M-JQ-JWD" firstAttribute="leading" secondItem="i5M-Pr-FkT" secondAttribute="leading" id="EwH-B1-XWY"/>
    </constraints>
</view>

Upvotes: 18

Martin
Martin

Reputation: 4765

If you are using interface builder, some constraints will be automatic copied if you use the cmd-c or edit/copy: the ones that include the copying view hierarchy. Otherwise, no, you can't. Copy the whole view if you want to preserve the constraints.

Upvotes: 20

Trianna Brannon
Trianna Brannon

Reputation: 1254

Here's my hack to get ALL the constraints to copy: I have a small view within my main view that I want to copy over to another view controller, in order to do this I copy over the entire main view into the new view controllers main view. I then drag my small view (on side hierarchy) into the main view of my new controller and then just deleted the old main view that I don't need. This way you keep all the constraints for the items within the small view.

Hope this helps :)

Upvotes: 18

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