Swift Tips #34 - defer

#iOS #swift #softwaredeveloper #iosdeveloper

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[v_pradeilles]

Did you find this tip useful? Are you planning on using it in your apps? Let me know in the comments 🚀

[keithweiss]

Your explanation of the drawbacks are super helpful. Thanks

[JumpingCow]

Something like the Python "with" statement would be nice.

[hellaandrew]

I used defer yesterday! My function, which was a button press handler, had several exit paths since I had to do something different based on an AB test value. I used defer to ensure that my analytics code will get called no matter what.

[DavidPetersonAU]

I'm a bit surprised that common things like file handling don't have a built-in closure-based API, along the lines of:

```
extension FileHandle {
public static func forReading(atPath: String, handler: (FileHandle?) throws -> Void) rethrows {
let file = FileHandle(forReadingAtPath: atPath)
defer { file?.closeFile() }
try handler(file)
}
}

try "~/temp.txt") { file in
guard let data = try? file?.readToEnd() else { return }
// use the data
}
```

Obviously, sometimes you keep files around longer than a single function call so you need the alternateive too, but it's a pretty common usecase.