当四个按钮中的任何一个被点击时,指示器总是第一次移动到最左边按钮下方的位置。但我想看到的是指示器滑动到刚被点击的按钮正下方的位置。这四个按钮在 Storyboard中被标记为 0、1、2、3。为什么?提前致谢!
class MainViewController: UIViewController {
@IBOutlet weak var weatherBtn: UIButton!
@IBOutlet weak var tourismBtn: UIButton!
@IBOutlet weak var tectonicsBtn: UIButton!
@IBOutlet weak var foodBtn: UIButton!
@IBOutlet weak var indicator: UIImageView!
var btnsArray: [UIButton]!
let tin = UIColor(red: 145/255, green: 145/255, blue: 145/255, alpha: 1)
override func viewDidLoad() {
super.viewDidLoad()
btnsArray = [weatherBtn, tourismBtn, tectonicsBtn, foodBtn]
indicator.image = UIImage().solidColor(.black, size: indicator.frame.size)
}
@IBAction func topicBtnTapped(_ sender: UIButton) {
indicate(button: sender)
}
func indicate(button: UIButton) {
UIView.animate(withDuration: 0.3) {
self.indicator.center.x = (button.superview?.frame.minX)! + button.frame.width * 0.5 * (2 * CGFloat(button.tag) + 1)
}
for btn in btnsArray {
btn.titleLabel?.textColor = tin
}
button.setTitleColor(.black, for: .normal)
}
}
extension UIImage {
func solidColor(_ color: UIColor, size: CGSize) -> UIImage {
let rect = CGRect(x: 0, y: 0, width: size.width, height: size.height)
UIGraphicsBeginImageContextWithOptions(size, false, 0)
color.setFill()
UIRectFill(rect)
let image: UIImage = UIGraphicsGetImageFromCurrentImageContext()!
UIGraphicsEndImageContext()
return image
}
}
最佳答案
假设您正在使用自动布局约束...
对于您的“指示器”UIImageView
,设置宽度和高度限制,以及天气按钮底部的垂直间距限制。
然后,将其限制在您的“天气”按钮水平居中。
为该 centerX 约束添加一个 IBOutlet:
@IBOutlet var indicatorCenterXConstraint: NSLayoutConstraint!
然后,当你想移动“指示器”时:
// deactivate indicator's current centerXAnchor
self.indicatorCenterXConstraint.isActive = false
// re-init to center aligned to selected button
self.indicatorCenterXConstraint = self.indicator.centerXAnchor.constraint(equalTo: button.centerXAnchor)
// set it active
self.indicatorCenterXConstraint.isActive = true
// animate it into place
UIView.animate(withDuration: 0.3) {
self.view.layoutIfNeeded()
}
因此,每次点击“菜单”按钮时,都会停用当前的 centerXAnchor,将其重新初始化为所点击按钮的 centerXAnchor,重新激活它,并为其设置动画。
这是完整的类(class):
class MenuMainViewController: UIViewController {
@IBOutlet weak var weatherBtn: UIButton!
@IBOutlet weak var tourismBtn: UIButton!
@IBOutlet weak var tectonicsBtn: UIButton!
@IBOutlet weak var foodBtn: UIButton!
@IBOutlet weak var indicator: UIImageView!
// outlet to control the position of the indicator
@IBOutlet var indicatorCenterXConstraint: NSLayoutConstraint!
var btnsArray: [UIButton]!
let tin = UIColor(red: 145/255, green: 145/255, blue: 145/255, alpha: 1)
override func viewDidLoad() {
super.viewDidLoad()
btnsArray = [weatherBtn, tourismBtn, tectonicsBtn, foodBtn]
indicator.image = UIImage().solidColor(.black, size: indicator.frame.size)
// init button title colors
for btn in btnsArray {
btn.setTitleColor(tin, for: .normal)
}
// set first button to "active" color
weatherBtn.setTitleColor(.black, for: .normal)
}
@IBAction func topicBtnTapped(_ sender: UIButton) {
indicate(button: sender)
}
func indicate(button: UIButton) {
// deactivate indicator's current centerXAnchor
self.indicatorCenterXConstraint.isActive = false
// re-init to center aligned to selected button
self.indicatorCenterXConstraint = self.indicator.centerXAnchor.constraint(equalTo: button.centerXAnchor)
// set it active
self.indicatorCenterXConstraint.isActive = true
// animate it into place
UIView.animate(withDuration: 0.3) {
self.view.layoutIfNeeded()
}
// update button title colors
for btn in btnsArray {
btn.setTitleColor(tin, for: .normal)
}
button.setTitleColor(.black, for: .normal)
}
}
顺便说一句,您可以使用带有 .backgroundColor = .black
的普通 UIView
,而不是为您的“指示器”imageView 创建纯色图像.
关于ios - 第一次操作按钮的错误行为,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/51896875/