CODEWITHSUNDEEP
arraysswiftfilterswift4
Viper8
Viper8

Reputation: 103

Pass function to array filter function error - Swift 4

I'm trying to extend the array class writing a simple function that will receive a function as parameter and will use that to filter the current array.

In this example "self" is actually an array.

this is what I used so far:

    func applyFilter(filterFunction: (String) -> Bool) {
    self.filter(filterFunction)
    }

But I'm receiving this error from xCode:

cannot convert value of type '(String) -> BOOL' to expected argument type '_ ' -> Bool

Any ideas?

Upvotes: 0

Views: 540

Answers (1)

Harry Wright
Harry Wright

Reputation: 306

The error message means that, the generic Array.filter(_:) function is expecting the Array.Element to be passed not a string.

If you change the extension and function to be:

extension Array where Element == String {

    func applyFilter(_ filter: (String) -> Bool) {
        self.filter(filter)
    }

}

As this specifies that the function will only be dealing with String elements then you can pass a function to the closure as such:

func filter(_ value: String) -> Bool { 
    /* Filter how you need */ 
}

["Hello", "World"].applyFilter(filter(_:))

Upvotes: 3

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