faster getting way than filter+first.

filter_first_instead_way.swift

import CoreFoundation

extension Array {
    func firstMatchFilter<T: Equatable>(target: T) -> Element? {
        let start = CFAbsoluteTimeGetCurrent()
        guard let index = self.indexOf({ $0 as! T == target }) else {
            return nil
        }
        let end = CFAbsoluteTimeGetCurrent()
        print("elapsed time = \(end - start)")
        return self[index]
    }

    func firstMatchFilter(@noescape predicate: (Element) throws -> Bool) rethrows -> Element? {
        let start = CFAbsoluteTimeGetCurrent()
        guard let index = try self.indexOf(predicate) else {
            return nil
        }
        let end = CFAbsoluteTimeGetCurrent()
        print("elapsed time = \(end - start)")
        return self[index]
    }
    
    func filterFirst<T: Equatable>(target: T) -> Element? {
        let start = CFAbsoluteTimeGetCurrent()
        let result = filter { $0 as! T == target }.first
        let end = CFAbsoluteTimeGetCurrent()
        print("elapsed time = \(end - start)")
        return result
    }
}

var array = [Int]()
for i in 0...1000 {
    array.append(i)
}

//array.firstMatchFilter(1)       // elapsed time : about 1ms
//array.filterFirst(1)            // elapsed time : about 300ms

//array.firstMatchFilter(500)     // elapsed time : about 150ms
//array.filterFirst(500)          // elapsed time : about 300ms

//array.firstMatchFilter(1000)    // elapsed time : about 300ms
//array.filterFirst(1000)         // elapsed time : about 300ms

array.firstMatchFilter { $0 == 500 }