Cannot compile Storyboard for iOS 7

Question

We have a Swift project for an UIKit app that is using Storyboards. Everything was fine until I decided to lower the Minimum deployment target of the app to iOS 7. When building the app I hit an assert in the ibtool which is trying to compile the storyboard. The error goes like this:

2015-06-12 11:49:07.216 ibtoold[41058:6974134] [MT] DVTAssertions: ASSERTION FAILURE in /SourceCache/IDEInterfaceBuilder/IDEInterfaceBuilder-7702/InterfaceBuilderKit/Connections/IBConnection.m:182
Details:  Source and destination must be unique
Object:   <IBCocoaTouchStoryboardPushSegue: 0x7fdea9bce8a0>
Method:   -setDestination:
Thread:   <NSThread: 0x7fdea2c07820>{number = 1, name = main}
Hints: None
Backtrace:
  0  0x00000001015e0147 -[DVTAssertionHandler handleFailureInMethod:object:fileName:lineNumber:assertionSignature:messageFormat:arguments:] (in DVTFoundation)
  1  0x00000001015dfb9f _DVTAssertionHandler (in DVTFoundation)
  2  0x00000001015dfe8e _DVTAssertionFailureHandler (in DVTFoundation)
  3  0x00000001023ff472 -[IBConnection setDestination:] (in IDEInterfaceBuilderKit)
  4  0x00000001023fe5c9 +[IBConnection connectionWithSource:label:andDestination:] (in IDEInterfaceBuilderKit)
  5  0x00000001086aa798 (in IDEInterfaceBuilderCocoaTouchIntegration)
  6  0x0000000108704abb (in IDEInterfaceBuilderCocoaTouchIntegration)
  7  0x0000000102481472 -[IBDocument updateConnectionsAfterEnablingOrDisablingConfigurations] (in IDEInterfaceBuilderKit)
  8  0x0000000102482194 __35-[IBDocument disableConfigurations]_block_invoke (in IDEInterfaceBuilderKit)
  9  0x0000000102481beb -[IBDocument maintainCanvasCentersWhileTransformingCanvasPositions:] (in IDEInterfaceBuilderKit)
 10  0x000000010248209c -[IBDocument disableConfigurations] (in IDEInterfaceBuilderKit)
 11  0x000000010868852c (in IDEInterfaceBuilderCocoaTouchIntegration)
 12  0x0000000102497469 -[IBDocumentAutolayoutManager runBlockInNewArbitrationStackEntryWithBehavior:block:] (in IDEInterfaceBuilderKit)
 13  0x000000010247de2b -[IBDocument modifyViewsInAutolayoutSafeWayDuring:] (in IDEInterfaceBuilderKit)
 14  0x00000001086884e2 (in IDEInterfaceBuilderCocoaTouchIntegration)
 15  0x000000010865d1e5 (in IDEInterfaceBuilderCocoaTouchIntegration)
 16  0x000000010244628f -[IBDocument finishChangingTargetRuntimeInCompiledIntermediateDocument] (in IDEInterfaceBuilderKit)
 17  0x00000001024a5811 __85-[IBDocumentCompiler invokeWithIntermediateDocumentOfTargetRuntime:alwaysCopy:block:]_block_invoke (in IDEInterfaceBuilderKit)
 18  0x00000001024a55a9 -[IBDocumentCompiler invokeWithIntermediateDocument:] (in IDEInterfaceBuilderKit)
 19  0x00000001024a574d -[IBDocumentCompiler invokeWithIntermediateDocumentOfTargetRuntime:alwaysCopy:block:] (in IDEInterfaceBuilderKit)
 20  0x00000001026aa61c -[IBStoryboardDocumentCompiler compileWithOptions:error:] (in IDEInterfaceBuilderKit)
 21  0x00000001024a5937 +[IBDocumentCompiler compileContentsOfDocument:options:error:] (in IDEInterfaceBuilderKit)
 22  0x0000000102460550 __47-[IBDocument compiledPackageWithOptions:error:]_block_invoke (in IDEInterfaceBuilderKit)
 23  0x0000000102498ee5 -[IBDocumentAutolayoutManager assertIfArbitrationIsScheduledDuring:] (in IDEInterfaceBuilderKit)
 24  0x00000001024604a7 -[IBDocument compiledPackageWithOptions:error:] (in IDEInterfaceBuilderKit)
 25  0x00000001013e9f0a (in ibtoold)
 26  0x00000001013e6b40 (in ibtoold)
 27  0x00000001013e9370 (in ibtoold)
 28  0x00000001013ef233 (in ibtoold)
 29  0x00000001013ef7b0 (in ibtoold)
 30  0x00000001013ef683 (in ibtoold)
 31  0x00000001013de60a (in ibtoold)
 32  0x00000001013eee2c (in ibtoold)
 33  0x00000001013ee074 (in ibtoold)
 34  0x00007fff9289f5c9 start (in libdyld.dylib)
 35  0x0000000000000002
Command /Applications/Xcode.app/Contents/Developer/usr/bin/ibtool failed with exit code 255

I checked all segues (and they are a lot) but I din't seem to see something wrong. Also when the Minimum deployment target is 8.x there is not a problem.

Answer 1

NOTE - This all came about from manually adding a referencing outlet to a UI element. I shortly after found out that I did NOT need to do that, and isntead simply adding a TAG was all I needed, since I just wanted to be able to access the element programmatically to hide/show it (Can I get the element by Tag from iPhone SDK?).

Anyway...

Don't know if this necessarily applies to OP, but maybe it will help a googler:

I ran into this error when I was manually adding a referencing outlet in the storyboard by editing the .xib's XML directly, instead of using the interface builder.

The reason: I wanted to add a referencing outlet to a label I had. However, when I used "New Referencing Outlet" in the interface builder, the IBOutlet I wanted did not show up on the list. So, I took the "bash it with a hammer until it works" approach and decided to manually add the referencing outlet in the XML.

A referencing outlet looks like this: <outlet property="nameOfTheVar" destination="9CH-Ow-gWo" id="8CH-Ow-hWo"/>

The destination is the id of the UI element that this is an outlet for, and id is a unique id for the referencing outlet.

An <outlet> should be a child of a <connections> element (Make's sense, it is connecting my UI element to in IBOutlet in code). My <label> has a <connections> element, and so I added the outlet there. That is what caused my Source and destination must be unique error. I guess it doesn't like a outlet to be a child of the element it is an outlet for.

So, to fix the error I moved the <outlet> from the <connections> element that was a child of the actual UI element, to the <connections> element that was a child of the <viewController> of that view.

Here is the (highly abbreviated) XML:

<viewController>
    <layoutGuides />
    <view>
        <subviews>
            <label id="9CH-Ow-gWo">
                <connections>
                    <!-- dont put the outlet here -->
                </connections>
            </label>
        </subviews>
    </view>
    <connections>
        <!--put the outlet here! -->
        <outlet property="nameOfTheVar" destination="9CH-Ow-gWo" id="8CH-Ow-hWo"/>
    </connections>
</viewController>