Recording iOS Simulator produces empty files

Question

I am trying to record the screen of my iOS 11.4 simulator with xcrun simctl io booted recordVideo recording.mov. This creates a file with that name, but unfortunately that file always has the size of 0 byte. Playing around with the --type parameter did not help either. Occasionally there was a playable file, which also was corrupted to a degree, as this file had a distorted look to it when opened in QuickTime. VLC could not play it at all.

I am using Xcode 9.4.1 on a 2014 MacBook Pro with discrete GPU, so Metal is supported.

Does anyone have suggestions to solve my problem?

You should look at @Harish's answer, it solved my problem... — Zaphod, Jul 12 '18 at 12:24

score 4 · Accepted Answer · answered Jul 01 '18 at 05:10

4

There was a timing bug in video recording that could result in 0-byte files on some systems. I'm sorry, but there is unfortunately no workaround. This should be addressed with changes in Xcode 10 Beta 3+.

answered Jul 01 '18 at 05:10

Jeremy Huddleston Sequoia

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Indeed it's failing for me in Xcode 9.4.1 and Xcode 10 Beta 2, but I just tried Xcode Beta 4 and it worked, although the video produced had some strange glitches as if the image was melting :( – endavid Jul 27 '18 at 21:21

score 2 · Answer 2 · answered Jun 30 '18 at 16:47

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I had that same issue and was scratching my head over that for days. The fix turns out to be simple though. Make sure you press Control + C and quit the simulator. Once you quit the simulator it starts to actually produce the recording.

answered Jun 30 '18 at 16:47

Harish

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You just saved my life ! – Zaphod Jul 12 '18 at 11:55
The key step is quitting the simulator. This worked for me with Xcode 9.4 but there were a lot of visual artifacts in the video – wyu Aug 01 '18 at 16:39

David S. · Answer 3 · 2018-06-29T20:36:05.503

You have to specify the device you want to record, and "booted" isn't valid.

Run this to see what's booted:

xcrun simctl list | grep Booted

In my case I see:

iPhone X (D3DB2489-B630-42AB-A615-A2F07F6F6876) (Booted)

To record this device:

xcrun simctl io D3DB2489-B630-42AB-A615-A2F07F6F6876 recordVideo ~/simrecord.mov

Here's example output from my terminal:

[ ~] xcrun simctl list | grep Booted
    iPhone X (D3DB2489-B630-42AB-A615-A2F07F6F6876) (Booted)
[ ~] xcrun simctl io D3DB2489-B630-42AB-A615-A2F07F6F6876 recordVideo ~/simrecord.mov
GVA encoder info: recomputed for fps: 11.353266, gop size in pics: 340, gop size in sec: 30.000000 
Recording... (Press CTRL+C to stop)
^C
Recording completed.
[ ~] ls -lrt | tail -1
-rw-r--r--    1 shawd  staff  32933285 Jun 29 16:34 simrecord.mov

One other thing to mention is that you can also record the simulator with Quicktime on the Mac pretty easily. That's what most people do.

Thank you for your suggestion, but unfortunately this does give me the same 0 byte sized file. — NKO, Jun 29 '18 at 07:03
You know you have to stop the recording before the file is written, yes? Updated my answer with terminal output. — David S., Jun 29 '18 at 20:35

Recording iOS Simulator produces empty files

3 Answers3