使用Swift,我该如何制作:
- 一个带有“开始”字样的按钮,并且当点击后可以无限次地切换为“暂停”和“开始”?(例如在秒表应用中)
- 一个自定义图片按钮,当点击后可以切换两张不同的图片,并且可以无限次进行此操作?
startPauseButton.setTitle("Start", forState: .Normal)
startPauseButton.setTitle("Pause", forState: .Selected)
IBAction func
中,将button.selected
属性在true
和false
之间切换。@IBAction func toggleStopwatch(button:UIButton) {
if button.selected {
// Pause the stopwatch
} else {
// Start the stopwatch
}
button.selected = !button.selected
}
UIButton
- 无论是通过更改代码还是通过在Interface Builder中连接时更新Type为UIButton
弹出窗口。 - Ashley Mills步骤1:创建一个布尔变量
var isPlaying:Bool = false
步骤二:将您的按钮与此IBAction方法连接:
@IBAction func btnStartStop(sender: UIButton) {
if isPlaying{
isPlaying = false
sender.setTitle("Pause", forState: UIControlState.Normal)
sender.setImage(pauseImage, forState: .Normal)
//Pause Stopwatch
}
else{
isPlaying = true
sender.setTitle("Play", forState: UIControlState.Normal)
sender.setImage(playImage, forState: .Normal)
//Play Stopwatch
}
}
Bool
来存储状态。 - Ashley Mills@IBAction func pressbutton(sender: UIButton) {
switch sender.titleLabel?.text {
case "Play":
play()
case "Pause":
pause()
default:
other()
}
sender.titleLabel?.text = "Whatever you want"
}
images
数组):@IBAction func pressbutton(sender: UIButton) {
switch sender.imageView!.image! {
case images[0]:
play()
case images[1]:
pause()
default:
other()
}
sender.imageView?.image = UIImage(...)
}
selected
的方式更好。 - vrwim试试这个……
@IBAction func btnStopWatch(sender: UIButton) {
if btnStopWatch.selected == true {
btnStopWatch.setTitle("stop", forState: UIControlState.Normal)
btnStopWatch.setImage(stopImage, forState: UIControlState.Normal)
btnStopWatch.selected = false
} else {
btnStopWatch.setTitle("start", forState: UIControlState.Normal)
btnStopWatch.setImage(startImage, forState: UIControlState.Normal)
btnStopWatch.selected = true
}
}
UIButton
标题在 Swift 3 中,UIButton
有一个名为 setTitle(_:for:)
的方法。 setTitle(_:for:)
具有以下声明:
func setTitle(_ title: String?, for state: UIControlState)
setTitle(_:for:)
来根据按钮的状态切换标题:import PlaygroundSupport
import UIKit
class ViewController: UIViewController {
override func viewDidLoad() {
super.viewDidLoad()
view.backgroundColor = UIColor.white
let button = UIButton(type: UIButtonType.system)
button.addTarget(self, action: #selector(toggle(sender:)), for: UIControlEvents.touchUpInside)
// Set button's states
button.setTitle("Start", for: UIControlState.normal)
button.setTitle("Pause", for: UIControlState.selected)
// set layout
view.addSubview(button)
button.translatesAutoresizingMaskIntoConstraints = false
let horizontalConstraint = button.centerXAnchor.constraint(equalTo: view.centerXAnchor)
let verticalConstraint = button.centerYAnchor.constraint(equalTo: view.centerYAnchor)
NSLayoutConstraint.activate([horizontalConstraint, verticalConstraint])
}
/// trigger action when button is tapped
func toggle(sender: UIButton) {
sender.isSelected = !sender.isSelected
print("Button state: \(sender.isSelected)")
}
}
let vc = ViewController()
PlaygroundPage.current.liveView = vc
使用 View > Assistant Editor > Show Assistant Editor 在 Playground 辅助编辑器中预览您的视图控制器。
UIButton
图片UIButton
有一个名为 setImage(_:for:)
的方法。 setImage(_:for:)
具有以下声明:
func setImage(_ image: UIImage?, for state: UIControlState)
setImage(_:for:)
来根据按钮的状态切换标题:import PlaygroundSupport
import UIKit
class ViewController: UIViewController {
override func viewDidLoad() {
super.viewDidLoad()
view.backgroundColor = UIColor.white
let button = UIButton()
button.addTarget(self, action: #selector(toggle(sender:)), for: UIControlEvents.touchUpInside)
// Set button's states
button.setImage(UIImage(named: "on.png"), for: UIControlState.normal)
button.setImage(UIImage(named: "off.png"), for: UIControlState.selected)
// set layout
view.addSubview(button)
button.translatesAutoresizingMaskIntoConstraints = false
let horizontalConstraint = button.centerXAnchor.constraint(equalTo: view.centerXAnchor)
let verticalConstraint = button.centerYAnchor.constraint(equalTo: view.centerYAnchor)
let heightConstraint = button.heightAnchor.constraint(equalToConstant: 100)
let widthConstraint = button.widthAnchor.constraint(equalToConstant: 100)
NSLayoutConstraint.activate([horizontalConstraint, verticalConstraint, heightConstraint, widthConstraint])
}
/// trigger action when button is tapped
func toggle(sender: UIButton) {
sender.isSelected = !sender.isSelected
print("Button state: \(sender.isSelected)")
}
}
let vc = ViewController()
PlaygroundPage.current.liveView = vc
使用 View > Assistant Editor > Show Assistant Editor 在 Playground 辅助编辑器中预览您的视图控制器。