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Remove all instances of an object from an array

Paul Hudson       @twostraws

Arrays already have methods to find and remove a single item, or remove all items at once, but they don’t have a built-in way to remove all instances of a single item. For example, how would you remove all the 2s in the following array?

var numbers = [2, 1, 2, 3, 2, 4, 2, 5]

Fortunately we can fix this using a simple extension to Array that runs all the items through filter() and returns any that don’t match whatever item you want removed:

extension Array where Element: Equatable {
    mutating func remove(_ obj: Element) {
        self = self.filter { $0 != obj }
    }
}

Now you can write numbers.remove(2) to get back [1, 3, 4, 5].

Available from iOS 8.0

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