対処法: unrecognized selector sent to instance | Swift6 入門書-逆引き大全集

Swift 6での書き方

文字列でselectorを書くとメソッド名や引数の間違いが実行時エラーになることがあるよ。現在は@objcメソッドと#selectorを使うと、対象の存在をコンパイラでも確認できるよ。

import UIKit

class TapExample: UIViewController {
    let textView = UITextView()

    override func viewDidLoad() {
        super.viewDidLoad()
        view.addSubview(textView)
        textView.frame = view.bounds
        let tap = UITapGestureRecognizer(target: self, action: #selector(doubleTapped(_:)))
        tap.numberOfTapsRequired = 2
        textView.addGestureRecognizer(tap)
    }

    @objc func doubleTapped(_ sender: UITapGestureRecognizer) {
        print("ダブルタップされました")
    }
}

import UIKit

class TapExample: UIViewController {

let textView = UITextView()

override func viewDidLoad() {

super.viewDidLoad()

view.addSubview(textView)

textView.frame = view.bounds

let tap = UITapGestureRecognizer(target: self, action: #selector(doubleTapped(_:)))

tap.numberOfTapsRequired = 2

textView.addGestureRecognizer(tap)

}

@objc func doubleTapped(_ sender: UITapGestureRecognizer) {

print("ダブルタップされました")

}

以下は旧バージョン当時の記録

unrecognized selector sent to instance というエラー。

問題があったコード

let tap = UITapGestureRecognizer(target: self, action: "doubleTapped")
tap.numberOfTapsRequired = 2
textView.addGestureRecognizer(tap)

let tap = UITapGestureRecognizer(target: self, action: "doubleTapped")

tap.numberOfTapsRequired = 2

textView.addGestureRecognizer(tap)

修正したコード

let tap = UITapGestureRecognizer(target: self, action: "doubleTapped:")
tap.numberOfTapsRequired = 2
textView.addGestureRecognizer(tap)

let tap = UITapGestureRecognizer(target: self, action: "doubleTapped:")

tap.numberOfTapsRequired = 2

textView.addGestureRecognizer(tap)

doubleTapped → doubleTapped:

これでおk