ios - 第一次操作按钮的错误行为
问题描述
当四个按钮中的任何一个被轻敲时,指示器总是第一次动画到最左边的按钮下方的位置。但我想看到的是,指示器滑到刚刚点击的按钮正下方的位置。这四个按钮在情节提要中被标记为 0、1、2、3。为什么?先感谢您!
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
}
}
解决方案
假设您正在使用自动布局约束...
对于您的“指标” UIImageView
,设置宽度和高度约束,以及在天气按钮底部的垂直间距约束。
然后,将其水平居中约束到您的天气按钮。
为 centerX 约束添加一个 IBOutlet:
@IBOutlet var indicatorCenterXConstraint: NSLayoutConstraint!
然后,当您要移动“指标”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,将其重新初始化为点击按钮的 centerXAnchor,重新激活它并为其设置动画。
这是完整的课程:
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)
}
}
并且,顺便说一句,您可以使用UIView
带有.backgroundColor = .black
.
推荐阅读
- javascript - 在 Three.js 和 React.js 中使用不受光线影响的 3D 对象在场景中制作 2D 图像?
- sql - SQL Server 将具有相同值的行组合成 JSON 对象
- reactjs - 如何使用 Jest 模拟 React 组件静态方法
- arrays - 试图从我的嵌套结构创建一个数组
- linux - 如何在终端命令 ocaml 中使用模块和脚本?
- python - PySide:有时我删除和添加项目时 QListWIdget 项目消失
- python - Plotly 在 Microsoft Edge 中打开图表
- php - htaccess RewriteRule 以任意顺序生成带有 2 个参数的 url
- javascript - 表单数据不会使用 onChange() 绑定到 React 组件
- c - getc 和 fgetc 不起作用...给出分段错误