@IBDesignable crashing agent

When I write my own UIButton-extended class and make it @IBDesignable, I receive two errors in Interface Builder, namely:

• Main.storyboard: error: IB Designables: Failed to update auto layout status: The agent crashed because the fd closed
• Main.storyboard: error: IB Designables: Failed to render instance of RandjeUIButton: The agent crashed

Here is my code:

import UIKit

@IBDesignable
class RandjeUIButton: UIButton {
    required init(coder aDecoder: NSCoder) {
        super.init(coder: aDecoder)
        
        self.backgroundColor = UIColor.blackColor()
    }
}

I am working in Xcode 7 beta 2 on OS X 10.11 beta 2. (Running in VM)

Xcode's Interface Builder requires that you implement both or neither initializers for @IBDesignable classes to render properly in IB.

If you implement required init(coder aDecoder: NSCoder) you'll need to override init(frame: CGRect) as well, otherwise "the agent will crash" as seen in the errors thrown by Xcode.

To do so add the following code to your class:

override init(frame: CGRect) {
    super.init(frame: frame)
}

I've met the same problem and solved it this way:

1. The Problem：

error: IB Designables: Failed to update auto layout status: The agent crashed

2. Find the debug button in the inspection file and click it.

3. Then the Xcode will tell you where the prolem is. In my case I drop the IBDesignable before the class.

4. Then I clean and rebuild it, the error disappeared

There are a myriad of problems that can cause this. Fire up Console, and look for the crash report IBDesignablesCocoaTouch...

I just sorted out a problem with a 3rd party designable which had issues with the valueForKey semantics.

In Xcode 7.3, none of the above solutions worked for me, but the accepted answer to this question did: https://stackoverflow.com/questions/26799054/failed-to-render-instance-of-ib-designables#answer-26812639

>

1. Clear Xcode derived data for the project. They are in ~/Library/Developer/Xcode/DerivedData
2. Clean your current build by pressing ⌘⇧K
3. Build your project
4. In storyboard go to Editor menu and do Refresh All Views; wait for build to be completed and errors should be gone

I did not need to do the 4th step to solve the problem (and get my PaintCode-drawRect'd UIView to paint in the storyboard), included here just in case.

Credit to @Mojtaba and @WeZZard

For me, it was not using #if !TARGET_INTERFACE_BUILDER that got me. Basically I had some code that would result in accessing a path in my Bundle...

Bundle.main.path(forResource: "Foo", ofType: "plist")

The problem is that when running in IB (and not in your app), Bundle.main isn't your app...

(lldb) po Bundle.main
NSBundle </Applications/Xcode.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/Library/Xcode/Overlays> (loaded)

So the answer to this is simply to review your @IBDesignable UIView code carefully and use #if !TARGET_INTERFACE_BUILDER for anything (in my case calls to CoreLocation for example) that doesn't make sense when running at design time.

How I debugged and found this

This is what you see when using the Editor -> Debug Selected View while selecting your @IBDesignable UIView in your storyboard:

You'll then crash at the right location

In my case, as you can see initXXXX was doing an assert, which was crashing at design time, because it was looking for a value in file in my Bundle — which is Xcode, at design time.

I found something really important when using an UIImage in any class marked @IBDesignable. The classic UIImage init would crash the agent:

let myImage = UIImage(named: String) // crash the agent

The solution is to use this init method of UIImage:

let myImage = UIImage(named: String, in: Bundle, compatibleWith: UITraitCollection)

Working code example:

let appBundle = Bundle(for: type(of: self))
let myImage = UIImage(named: "myImage", in: bundle, compatibleWith: self.traitCollection))

Where self is your class with the @IBDesignable keyword. Xcode 9.4, Swift 4.1

XCode 10, Swift 4.2

I found an answer here

Solution was simple - changing the way the bundle was resolved in the required init?(coder aDecoder: NSCoder) method of my custom view class.

    Bundle.main.loadNibNamed(String(describing: TestView.self), owner: self, options: nil)

needed to be changed to

let bundle = Bundle(for: TestView.self)
bundle.loadNibNamed(String(describing: TestView.self), owner: self, options: nil)

This is how I solves this problem:

• Make sure the outlets are properly initialized
• @IBInspectable properties would be properly initialized
• in xib file, click on File's owner placeholder, Go to Identity inspector, make sure it wont have any default values

import UIKit

@IBDesignable class TestView: UIView {
    
    @IBOutlet weak var label: UILabel!
    
    
    @IBInspectable var textLabel1: String? {
        get {
            return label.text
        }
        set {
            label.text = newValue
        }
    }

    
    // MARK: Setup
    
    var view1: UIView!
    var nibName: String = "TestView"
    
    
    override init(frame: CGRect) {
        super.init(frame: frame)
        xibSetup()
    }
    
    required init?(coder aDecoder: NSCoder) {
        super.init(coder: aDecoder)
        xibSetup()
    }
    
    private func xibSetup() {
        view1 = loadViewFromNib()
        
        view1?.frame = self.bounds
        view1?.autoresizingMask = [.FlexibleWidth, .FlexibleHeight]
        
        if view1 != nil {
            addSubview(view1!)
            //textLabel1 = "ok"
        }
    }
    
    private func loadViewFromNib() -> UIView? {
        let bundle = NSBundle(forClass: self.dynamicType)
        let nib = UINib(nibName: nibName, bundle: bundle)
        for object in nib.instantiateWithOwner(self, options: nil) {
            if let view: UIView = object as? UIView {
                return view
            }
        }
        return nil
    }
    
    
}

Usage:

Just re-open a code on another Xcode setup System. In my case it Worked.

I wasted a full day on this and finally I got my problem solved

I selected Build for target as 8.0 and it fixes everything for me.