[英]Buttons Programmatically on Swift 4
一個快速的問題,我正在嘗試創建一個名為setupHeader()的函數,在該函數中,該函數會設置標題的所有視圖和按鈕。 問題出在“注銷”按鈕上,由於某種原因,我無法正確使用它。
第一個錯誤是按鈕的addTarget無法識別“自身”。 有什么建議么?
第二個問題是#selector僅與@objc函數一起使用,並且該函數不能在主setupHeader函數中。 我應該放在哪里? 這是我的代碼的片段:
import Foundation
import UIKit
func setupHeader(vc: UIViewController) {
let headerFiller: UIView = {
let view = UIView()
view.translatesAutoresizingMaskIntoConstraints = false
view.backgroundColor = supaGray
return view
}()
let header: UIView = {
let view = UIView()
view.translatesAutoresizingMaskIntoConstraints = false
view.backgroundColor = supaGray
return view
}()
let logOutButton: UIButton = {
let button = UIButton()
button.translatesAutoresizingMaskIntoConstraints = false
button.setTitle("Log Out", for: .normal)
button.setTitleColor(.blue, for: .normal)
button.titleLabel?.adjustsFontSizeToFitWidth = true
button.titleLabel?.textAlignment = .left
button.addTarget(self, action: #selector(handleLogOutButton), for: .touchUpInside)
return button
}()
func handleLogOutButton() {
}
vc.view.addSubview(header)
header.topAnchor.constraint(equalTo: vc.view.safeAreaLayoutGuide.topAnchor).isActive = true
header.leftAnchor.constraint(equalTo: vc.view.leftAnchor).isActive = true
header.rightAnchor.constraint(equalTo: vc.view.rightAnchor).isActive = true
header.heightAnchor.constraint(equalToConstant: 40).isActive = true
header.addSubview(logOutButton)
logOutButton.centerYAnchor.constraint(equalTo: header.centerYAnchor, constant: -5).isActive = true
logOutButton.leftAnchor.constraint(equalTo: header.leftAnchor, constant: 7).isActive = true
logOutButton.widthAnchor.constraint(equalTo: header.widthAnchor, multiplier: 0.17).isActive = true
logOutButton.heightAnchor.constraint(equalToConstant: 40).isActive = true
vc.view.addSubview(headerFiller)
headerFiller.topAnchor.constraint(equalTo: vc.view.topAnchor).isActive = true
headerFiller.leftAnchor.constraint(equalTo: vc.view.leftAnchor).isActive = true
headerFiller.rightAnchor.constraint(equalTo: vc.view.rightAnchor).isActive = true
headerFiller.bottomAnchor.constraint(equalTo: header.topAnchor).isActive = true
}
以這種方式聲明按鈕按下回調。
@objc func handleLogOutButton() {
}
對於自我錯誤,請使用vc作為函數的傳遞參數。
看來您要將視圖控制器傳遞到函數中,因此使用self無效。 嘗試使用“ vc”
很簡單:
修改您的代碼,如下所示:
lazy var logOutButton: UIButton = {
let button = UIButton()
button.translatesAutoresizingMaskIntoConstraints = false
button.setTitle("Log Out", for: .normal)
button.setTitleColor(.blue, for: .normal)
button.titleLabel?.adjustsFontSizeToFitWidth = true
button.titleLabel?.textAlignment = .left
button.addTarget(self, action: #selector(handleLogOutButton), for: .touchUpInside)
return button
}()
@objc func handleLogOutButton() {
// Do your things here
}
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