Category Archives: Uncategorized

TL;DR Applying data source snapshot didn’t reload existing items as expected. Apple’s updated doc is pretty comprehensive on the subject, and covers the issue. Though reload and reconfigure need to be done manually, at least there is now an “official” way to do it. The issue: Diffable Data Source won’t reload items automatically For someContinue reading “Reloading existing items when using Diffable Data Source”

While investigating some memory leak issue, I found out that if I po an object before using Memory Graph, that object would stay in memory forever, and Memory Graph would show something like NSKeyValueDependencyInfo as an owner of the object. A leak will also happen when using p or expression. See for more details: https://github.com/kastiglione/swift_po.

Last time I encountered this issue, it was hard to find the reason. We don’t know much about what actually UI Tests system waits for in such cases. There are rumours over internet that activity on main thread is what it looks for, but it’s not always the case. Let’s go over few tips thatContinue reading “Xcode UI Tests: infinite “wait for app to idle””

TL;DR Use snapshot() method of XCUIElement in order to get consistent element information. Asynchronous nature of UI Tests Tests happen in a separate process, Test Runner, that doesn’t have access to actual views of our App. Runner talks to App using some special communication channel, probably inter-process mechanism. Our code dispatches requests to this mechanism,Continue reading “UI Tests are asynchronous and dynamic. Issues and tips.”

The issue I am going to talk about is relevant to anyone who uses Core Data. It is an “invisible” issue that may show up so rarely that it’s almost impossible to debug. It is only catchable by repeated automated tests. Let’s take a look at the piece of code that has single perform(_:) whichContinue reading “Your Core Data fetches may return unexpected results, or why you should use Query Generations”

So you can’t make Swift’s autogenerated initialize to be public. But at least there is a way to generate it using Xcode’s Refactor menu. Thanks JP Aquino https://stackoverflow.com/a/56530814/2774520

Have you ever encountered a file without extension, and wondered what is this file? I have, but thank to Jamie Wong and his great article “Reverse Engineering Instruments’ File Format”, this seem to not be a trouble anymore. Meet file – a program that tries to guess the type of a file by looking atContinue reading “TIL unix “file” program”

For AVVideoComposition to work correctly, you should init AVMutableVideoCompositionLayerInstruction with AVCompositionTrack created by you, instead of AVAssetTrack provided by AVAsset. This may be unintuitive at first, because how do you apply instructions to the track you want? How do you do transitions if there is only one AVCompositionTrack? Well, you’d create two, and alternate betweenContinue reading “AVMutableVideoCompositionLayerInstruction assetTrack”