I was able to resolve the issue running `xcrun simctl erase all` in Terminal.

Quit Xcode.app, Simulator.app, etc

Try the following commands in Terminal

    sudo killall -9 com.apple.CoreSimulator.CoreSimulatorService    
    rm -rf ~/Library/*/CoreSimulator

Go to Xcode menu `Window`-&gt; `Devices and Simulators` -&gt; `Simulators` tab, right-click the bad simulator and choose `Delete` from the menu list, then add it back from the left bottom entry again, it works!

[![enter image description here][1]][1]


  [1]: https://i.stack.imgur.com/bLw1k.png

Click on the simulators dropdown at the top of Xcode, and select `Download Simulators...`.

[![Simulators Dropdown][1]][1]

From here, you can select which versions you want to download and for what devices.


  [1]: https://i.stack.imgur.com/IDmXW.png

Just run this command in terminal:

    xcrun simctl shutdown all &amp;&amp; xcrun simctl erase all

**I had the same issue.**

It worked for me by erasing the device which your Mac does not found.

    xcrun simctl erase AKADKJ-

Here is also a link where a found a good explanation.

https://medium.com/xcblog/simctl-control-ios-simulators-from-command-line-78b9006a20dc

I am storing a ref in my redux store and using mapStateToProps to expose the ref for components that need access to it.

The ref that is stored looks like:

    ref={node =&gt; this.myRefToBePutInReduxGlobalStore = node}

What is the correct propType for this ref? 


What is the correct proptype for a ref in React?

I started to learn Android Studio. I try to echo out simple &quot;Hello World&quot;:

    &lt;?xml version=&quot;1.0&quot; encoding=&quot;utf-8&quot;?&gt;
    &lt;RelativeLayout
        android:id=&quot;@+id/activity_main&quot;
        xmlns:android=&quot;http://schemas.android.com/apk/res/android&quot;
        xmlns:tools=&quot;http://schemas.android.com/tools&quot;
        android:layout_width=&quot;match_parent&quot;
        android:layout_height=&quot;match_parent&quot;
        android:paddingLeft=&quot;16dp&quot;
        android:paddingRight=&quot;16dp&quot;
        android:paddingTop=&quot;16dp&quot;
        android:paddingBottom=&quot;16dp&quot;
        tools:context=&quot;.MainActivity&quot;&gt;
    
        &lt;TextView
            android:layout_width=&quot;wrap_content&quot;
            android:layout_height=&quot;wrap_content&quot;
            android:text=&quot;Hello World!&quot; /&gt;
    
    &lt;/RelativeLayout&gt;

but when I clicked &quot;design&quot; view, this error is showing?

&gt; Design editor is unavailable until a successful build

How can I fix this error.

[![enter image description here][2]][2]

[![enter image description here][1]][1]

I just noticed that my xml code is causing error. Is that why this may be not working?


  [1]: https://i.stack.imgur.com/5CfeX.png
  [2]: https://i.stack.imgur.com/mf1cP.png

How can I fix &quot;Design editor is unavailable until a successful build&quot; error?

The device&#39;s data is no longer present at _/Users/[user name]/Library/Developer/CoreSimulator/Devices/D651BCC7-29FD-4B91-82F6-E255E856EA2F/data._

I uninstalled xcode 9 and installed xcode 9.1, but when run project, following message was shown:

&gt; Unable to boot device because it cannot be located on disk.
The device&#39;s data is no longer present at /Users/[user name]/Library/Developer/CoreSimulator/Devices/D651BCC7-29FD-4B91-82F6-E255E856EA2F/data.

I found &quot;Developer&quot; folder, but cannot find &quot;CoreSimulator&quot; folder.


Unable to boot device because it cannot be located on disk

The device's data is no longer present at /Users/[user name]/Library/Developer/CoreSimulator/Devices/D651BCC7-29FD-4B91-82F6-E255E856EA2F/data.
I uninstalled xcode 9 and installed xcode 9.1, but when run project, following message was shown:
> Unable to boot device because it cannot be located on disk.
The device's data is no longer present at /Users/[user name]/Library/Developer/CoreSimulator/Devices/D651BCC7-29FD-4B91-82F6-E255E856EA2F/data.
I found "Developer" folder, but cannot find "CoreSimulator" folder.

Warning: `leading or trailing horizontal alignment before iOS 11`

I am getting above warning during compilation on Xcode 9.1 on one of the scenes in a storyboard file. There are other storyboards *(with deployment target iOS 10.0)* and yet the warning is shown to this specific scene on a specific Storyboard file.

The warning gets suppressed if I change deployment target to iOS 11.0 on the scene where warning is shown but I don&#39;t want to do that.

Has anyone come across this case?

leading or trailing horizontal alignment before iOS 11

The documentation does not have any examples on how to add a subcollection to a document. I know how to add document to a collection and how to add data to a document, but how do I add a collection (subcollection) to a document?

Shouldn&#39;t there be some method like this:

    dbRef.document(&quot;example&quot;).addCollection(&quot;subCollection&quot;)

How to add subcollection to a document in Firebase Cloud Firestore

Working with my first application for learning purposes. It goes well but has met into a problem with Xcode. When I try to run the application on the iPhone simulator this message always pops up &quot;This app could not be installed at this time.&quot; 

[![screenshot][1]][1]

What is wrong? There are no errors when trying to build the app. Has tried to clean the build. Reinstall pods. Restarted Xcode. Erased all settings on the simulator device, however, the problems still exist. 

The error message does not give me any information. Is there another logfile I could look into or something? 


  [1]: https://i.stack.imgur.com/5Ahpd.png

Xcode: &quot;This app could not be installed at this time.&quot;

I&#39;ve read the [documentation](https://developer.apple.com/documentation/uikit/uiview/1622572-translatesautoresizingmaskintoco). But I&#39;m still not sure when I need to not set it to `false`. In the code below if I set it to `false` I won&#39;t see the header at all. If I leave it as `true`, then everything is fine.

The following in  View debug hierarchy will give a warning &quot;**width** and **position** are ambiguous&quot;. 

    func tableView(_ tableView: UITableView, viewForHeaderInSection section: Int) -&gt; UIView? {
        
        let header = UIView()
        header.translatesAutoresizingMaskIntoConstraints = false
        header.backgroundColor = .orange
        header.heightAnchor.constraint(equalToConstant: 10).isActive = true
            
        return header
    }

I thought whenever I need to modify anything in the code I would have to set `translatesAutoresizingMaskIntoConstraints` to `false`.

Perhaps it&#39;s more correct to say if you need to remove all its constraints then set it to `false` and then add what you like, and in that case you would need to add constraints for all 4 sides.

However, if you need to just keep what the system provides to you, in this case that would be the tableView managing its position and width then leave to `true`.

Is that right?


When should translatesAutoresizingMaskIntoConstraints be set to true?

I have a simple program HelloWorld running on iOS. The same code has been running fine for a long time. Recently, I notice that I get the below BoringSSL error when the program runs on my ipad connected to Xcode 9 on my Macbook. I don&#39;t see this error when I run the program in simulator. The iOS is 11.2. Xcode is 9.2.

My code has no reference to BoringSSL. However, it does use NSMutableURLRequest to make https call to a server. The call works fine and everything seems to work fine except the BoringSSL messages.

Is there a way the I can debug why the message comes up? HellowWorld[466:85961], what do those 2 numbers mean? 

What does the message mean and how to avoid it?

    2017-12-13 15:41:13.486047-0500 HellowWorld[466:85961] [BoringSSL] Function boringssl_session_errorlog: line 2871 [boringssl_session_read] SSL_ERROR_ZERO_RETURN(6): operation failed because the connection was cleanly shut down with a close_notify alert
    2017-12-13 15:41:13.486363-0500 HellowWorld[466:85961] [BoringSSL] Function boringssl_session_errorlog: line 2871 [boringssl_session_read] SSL_ERROR_ZERO_RETURN(6): operation failed because the connection was cleanly shut down with a close_notify alert

[![Screenshot added][1]][1]


  [1]: https://i.stack.imgur.com/cCLOV.png

Xcode 9 iOS 11 BoringSSL SSL_ERROR_ZERO_RETURN

I’ve been working on an app for a client using my own Apple Developer account so far while waiting for them to register a Developer account themselves.

They have done this— and the time has come for them to be able to build and run the project on their machine, but they’re getting this error:

`Code Signing Error: No account for team &quot;59xxxxxxxx&quot;. Add a new account in the Accounts preference pane or verify that your accounts have valid credentials.
Code Signing Error: No signing certificate &quot;iOS Development&quot; found:  No &quot;iOS Development&quot; signing certificate matching team ID &quot;59xxxxxxxx&quot; with a private key was found.`


The team ID in the error message is mine, what I’ve been using to build the project on my computers.

Their account has already been set in their Xcode&#39;s preferences pane, and I have been added as a member to that team. 

I have worked on other projects with other developers where we could build the project simply by selecting our respective Team in the drop-down menu within the Signing section of the General project settings. For some reason when my client selects their team and tries to build the project it still produces this error. 

Does anyone know what we&#39;re doing wrong?

Code Signing &quot;No account for team&quot; message when signing for different developer account

I&#39;m attempting to migrate an Xcode project to another computer. It gives me the warning &quot;Warning: unable to build chain to self-signed root for signer&quot; and when it runs it crashes immediately similarly to what is shown in this Stack Overflow:

https://stackoverflow.com/questions/48749912/app-working-on-simulator-but-not-on-iphone-dyld-abort-with-payload-dyld-dyld

My issue seems similar to what is described on the Apple Developer Forums here:
https://forums.developer.apple.com/thread/86161

and similar to what is described on this Stack Overflow:
https://stackoverflow.com/questions/47307416/xcode-ios-app-development-code-signing

except the suggestions of deleting certificates and re-adding them, re-adding my account and restarting didn&#39;t seem to help. I have removed my developer cert for the second time and now I don&#39;t see it coming back, and I&#39;m at a loss of knowing how to get it back since my dev portal doesn&#39;t appear to have a place to download it like it used to. 

I&#39;ve also tried deleting the derived data folder several times. 

e: I&#39;ve determined ANY project on this computer results in the same crash and warning.

Content Type	Original Author	Original Content on Stackoverflow
Question	Milan Jansen	View Question on Stackoverflow
Solution 1 - Ios	Tomáš Linhart	View Answer on Stackoverflow
Solution 2 - Ios	IKKA	View Answer on Stackoverflow
Solution 3 - Ios	Itachi	View Answer on Stackoverflow
Solution 4 - Ios	Nick Meehan	View Answer on Stackoverflow
Solution 5 - Ios	Levan Karanadze	View Answer on Stackoverflow
Solution 6 - Ios	michaeldibse	View Answer on Stackoverflow

Unable to boot device because it cannot be located on disk

Ios Problem Overview

Ios Solutions

Solution 1 - Ios

Solution 2 - Ios

Solution 3 - Ios

Solution 4 - Ios

Solution 5 - Ios

Solution 6 - Ios

How can I fix "Design editor is unavailable until a successful build" error?

What is the correct proptype for a ref in React?

Attributions