Weak self capturing in Swift closures

Weakify.swift

func weak<T: AnyObject>(_ obj: T, _ block: @escaping (T) -> () -> Void) -> () -> Void {
    return { [weak obj] in
        obj.map(block)?()
    }
}

func weak<T: AnyObject, Argument>(_ obj: T, _ block: @escaping (T) -> (Argument) -> Void) -> (Argument) -> Void {
    return { [weak obj] a in
        obj.map(block)?(a)
    }
}

// Usage

// Without weak

let doneHandler: () -> Void = { [weak self] in
    self?.deleteSmth()
}
let alertModel = AlertViewModel(message: "Delete something?",  doneHandler: doneHandler)
```​

// Using weak
`let alertModel = AlertViewModel(message: message: "Delete something?",  doneHandler: weak(self, ViewModel.deleteSomething)`