Swift - 子视图 frame.maxY 读取不正确
Swift - Subviews frame.maxY reading incorrectly
我有一个以编程方式设置的基本注册屏幕，其中的 UI 元素位于一个视图中，该视图本身位于滚动视图中。
屏幕中的最后一个 UI 元素是注册按钮。我使用 Will Show 和 Will Hide 通知设置了键盘通知观察器。
我在第 7 代 iPod touch 模拟器上 运行 这段代码。
我的问题是当尝试读取注册按钮的 maxY 值并将其与键盘 minY 进行比较时，它打印出错误的数字。
键盘明显挡住了注册按钮，这意味着按钮的 maxY 值将大于键盘的 minY 值。
但是打印的值显示注册按钮框架的读取有问题。
这是我的代码：
import UIKit
class RegisterVC: UIViewController {
private let scrollView: UIScrollView = {
let scroll = UIScrollView()
scroll.clipsToBounds = true
scroll.isScrollEnabled = true
scroll.translatesAutoresizingMaskIntoConstraints = false
scroll.showsVerticalScrollIndicator = false
return scroll
}()
private let scrollInnerView: UIView = {
let innerView = UIView()
innerView.translatesAutoresizingMaskIntoConstraints = false
return innerView
}()
private let profilePic: UIImageView = {
let imageView = UIImageView()
imageView.image = UIImage(systemName: "person.circle")
imageView.contentMode = .scaleAspectFit
imageView.tintColor = .gray
imageView.translatesAutoresizingMaskIntoConstraints = false
return imageView
}()
private let usernameField: UITextField = {
let field = UITextField()
field.autocapitalizationType = .none
field.autocorrectionType = .no
field.returnKeyType = .next
field.layer.cornerRadius = 12
field.layer.borderWidth = 1
field.layer.borderColor = UIColor.lightGray.cgColor
field.placeholder = "Username..."
field.leftView = UIView(frame: CGRect(x: 0, y: 0, width: 5, height: 0))
field.leftViewMode = .always
field.backgroundColor = .white
field.keyboardType = .default
field.isHighlighted = false
field.textAlignment = .left
field.translatesAutoresizingMaskIntoConstraints = false
return field
}()
private let emailField: UITextField = {
let field = UITextField()
field.autocapitalizationType = .none
field.autocorrectionType = .no
field.returnKeyType = .next
field.layer.cornerRadius = 12
field.layer.borderWidth = 1
field.layer.borderColor = UIColor.lightGray.cgColor
field.placeholder = "Email Address..."
field.leftView = UIView(frame: CGRect(x: 0, y: 0, width: 5, height: 0))
field.leftViewMode = .always
field.backgroundColor = .white
field.keyboardType = .default
field.textAlignment = .left
field.translatesAutoresizingMaskIntoConstraints = false
return field
}()
private let passwordField: UITextField = {
let field = UITextField()
field.autocapitalizationType = .none
field.autocorrectionType = .no
field.returnKeyType = .done
field.layer.cornerRadius = 12
field.layer.borderWidth = 1
field.layer.borderColor = UIColor.lightGray.cgColor
field.placeholder = "Password..."
field.leftView = UIView(frame: CGRect(x: 0, y: 0, width: 5, height: 0))
field.leftViewMode = .always
field.backgroundColor = .white
field.isSecureTextEntry = true
field.textAlignment = .left
field.keyboardType = .default
field.translatesAutoresizingMaskIntoConstraints = false
return field
}()
private let registerButton: UIButton = {
let button = UIButton()
button.setTitle("Create Account", for: .normal)
button.backgroundColor = .systemGreen
button.setTitleColor(.white, for: .normal)
button.layer.cornerRadius = 12
button.layer.masksToBounds = true
button.titleLabel?.font = .systemFont(ofSize: 20, weight: .bold)
button.translatesAutoresizingMaskIntoConstraints = false
return button
}()
override func viewDidLoad() {
super.viewDidLoad()
title = "Create Account"
view.backgroundColor = .white
view.addSubview(scrollView)
scrollView.addSubview(scrollInnerView)
scrollInnerView.addSubview(profilePic)
scrollInnerView.addSubview(usernameField)
scrollInnerView.addSubview(emailField)
scrollInnerView.addSubview(passwordField)
scrollInnerView.addSubview(registerButton)
usernameField.delegate = self
emailField.delegate = self
passwordField.delegate = self
profilePic.isUserInteractionEnabled = true
registerButton.addTarget(self,
action: #selector(registerButtonTapped),
for: .touchUpInside)
setUpKeyboard()
setUpConstraints()
}
private func setUpConstraints() {
// Scroll View Constraints
scrollView.topAnchor.constraint(equalTo: view.safeAreaLayoutGuide.topAnchor).isActive = true
scrollView.leadingAnchor.constraint(equalTo: view.leadingAnchor).isActive = true
scrollView.trailingAnchor.constraint(equalTo: view.trailingAnchor).isActive = true
scrollView.bottomAnchor.constraint(equalTo: view.safeAreaLayoutGuide.bottomAnchor).isActive = true
// Scroll Inner View Constraints
scrollInnerView.topAnchor.constraint(equalTo: scrollView.topAnchor).isActive = true
scrollInnerView.leadingAnchor.constraint(equalTo: scrollView.leadingAnchor).isActive = true
scrollInnerView.trailingAnchor.constraint(equalTo: scrollView.trailingAnchor).isActive = true
scrollInnerView.bottomAnchor.constraint(equalTo: scrollView.bottomAnchor).isActive = true
scrollInnerView.widthAnchor.constraint(equalTo: scrollView.widthAnchor).isActive = true
scrollInnerView.heightAnchor.constraint(equalTo: scrollView.heightAnchor, constant: 1).isActive = true
// Profile Picture Constraints
profilePic.widthAnchor.constraint(equalTo: scrollInnerView.widthAnchor, multiplier: 1/3).isActive = true
profilePic.heightAnchor.constraint(equalTo: scrollInnerView.widthAnchor, multiplier: 1/3).isActive = true
profilePic.centerXAnchor.constraint(equalTo: scrollInnerView.centerXAnchor).isActive = true
profilePic.topAnchor.constraint(equalTo: scrollInnerView.topAnchor, constant: 10).isActive = true
// User Name Field Constraints
usernameField.widthAnchor.constraint(equalTo: scrollInnerView.widthAnchor, constant: -60).isActive = true
usernameField.heightAnchor.constraint(equalToConstant: 45).isActive = true
usernameField.topAnchor.constraint(equalTo: profilePic.bottomAnchor, constant: 10).isActive = true
usernameField.centerXAnchor.constraint(equalTo: profilePic.centerXAnchor).isActive = true
// Email Field Constraints
emailField.widthAnchor.constraint(equalTo: usernameField.widthAnchor).isActive = true
emailField.heightAnchor.constraint(equalTo: usernameField.heightAnchor).isActive = true
emailField.topAnchor.constraint(equalTo: usernameField.bottomAnchor, constant: 10).isActive = true
emailField.centerXAnchor.constraint(equalTo: usernameField.centerXAnchor).isActive = true
// Password Field Constraints
passwordField.widthAnchor.constraint(equalTo: emailField.widthAnchor).isActive = true
passwordField.heightAnchor.constraint(equalTo: emailField.heightAnchor).isActive = true
passwordField.topAnchor.constraint(equalTo: emailField.bottomAnchor, constant: 10).isActive = true
passwordField.centerXAnchor.constraint(equalTo: emailField.centerXAnchor).isActive = true
// Register Button Constraints
registerButton.widthAnchor.constraint(equalTo: passwordField.widthAnchor).isActive = true
registerButton.heightAnchor.constraint(equalTo: passwordField.heightAnchor).isActive = true
registerButton.topAnchor.constraint(equalTo: passwordField.bottomAnchor, constant: 20).isActive = true
registerButton.centerXAnchor.constraint(equalTo: passwordField.centerXAnchor).isActive = true
}
private func setUpKeyboard() {
NotificationCenter.default.addObserver(self, selector: #selector(keyboardWillShowNotification), name: UIResponder.keyboardWillShowNotification, object: nil)
NotificationCenter.default.addObserver(self, selector: #selector(keyboardWillHideNotification), name: UIResponder.keyboardWillHideNotification, object: nil)
}
@objc private func keyboardWillShowNotification(_ notification: NSNotification) {
guard let keyboardSize = (notification.userInfo?[UIResponder.keyboardFrameEndUserInfoKey] as? NSValue)?.cgRectValue
else {
return
}
print(keyboardSize.minY)
print(registerButton.frame.maxY)
}
}
因为键盘边框和按键边框在两个不同的坐标系下。你不能直接比较它们。在比较它们之前，您需要 convert 按钮框架到 window 坐标。否则 将键盘框架转换 到按钮框架坐标（按钮的父视图）。
实际上我通常做的是将键盘框架转换为目标视图的内部坐标，并将其与目标视图的边界.例如：
// n is the notification
let d = n.userInfo!
var r = d[UIResponder.keyboardFrameEndUserInfoKey] as! CGRect
r = self.slidingView.convert(r, from:nil) // <- this is the key move!
let h = self.slidingView.bounds.intersection(r).height
这告诉我键盘是否会覆盖滑动视图，如果是，覆盖多少。
我有一个以编程方式设置的基本注册屏幕，其中的 UI 元素位于一个视图中，该视图本身位于滚动视图中。
屏幕中的最后一个 UI 元素是注册按钮。我使用 Will Show 和 Will Hide 通知设置了键盘通知观察器。
我在第 7 代 iPod touch 模拟器上 运行 这段代码。
我的问题是当尝试读取注册按钮的 maxY 值并将其与键盘 minY 进行比较时，它打印出错误的数字。
键盘明显挡住了注册按钮，这意味着按钮的 maxY 值将大于键盘的 minY 值。
但是打印的值显示注册按钮框架的读取有问题。
这是我的代码：
import UIKit
class RegisterVC: UIViewController {
private let scrollView: UIScrollView = {
let scroll = UIScrollView()
scroll.clipsToBounds = true
scroll.isScrollEnabled = true
scroll.translatesAutoresizingMaskIntoConstraints = false
scroll.showsVerticalScrollIndicator = false
return scroll
}()
private let scrollInnerView: UIView = {
let innerView = UIView()
innerView.translatesAutoresizingMaskIntoConstraints = false
return innerView
}()
private let profilePic: UIImageView = {
let imageView = UIImageView()
imageView.image = UIImage(systemName: "person.circle")
imageView.contentMode = .scaleAspectFit
imageView.tintColor = .gray
imageView.translatesAutoresizingMaskIntoConstraints = false
return imageView
}()
private let usernameField: UITextField = {
let field = UITextField()
field.autocapitalizationType = .none
field.autocorrectionType = .no
field.returnKeyType = .next
field.layer.cornerRadius = 12
field.layer.borderWidth = 1
field.layer.borderColor = UIColor.lightGray.cgColor
field.placeholder = "Username..."
field.leftView = UIView(frame: CGRect(x: 0, y: 0, width: 5, height: 0))
field.leftViewMode = .always
field.backgroundColor = .white
field.keyboardType = .default
field.isHighlighted = false
field.textAlignment = .left
field.translatesAutoresizingMaskIntoConstraints = false
return field
}()
private let emailField: UITextField = {
let field = UITextField()
field.autocapitalizationType = .none
field.autocorrectionType = .no
field.returnKeyType = .next
field.layer.cornerRadius = 12
field.layer.borderWidth = 1
field.layer.borderColor = UIColor.lightGray.cgColor
field.placeholder = "Email Address..."
field.leftView = UIView(frame: CGRect(x: 0, y: 0, width: 5, height: 0))
field.leftViewMode = .always
field.backgroundColor = .white
field.keyboardType = .default
field.textAlignment = .left
field.translatesAutoresizingMaskIntoConstraints = false
return field
}()
private let passwordField: UITextField = {
let field = UITextField()
field.autocapitalizationType = .none
field.autocorrectionType = .no
field.returnKeyType = .done
field.layer.cornerRadius = 12
field.layer.borderWidth = 1
field.layer.borderColor = UIColor.lightGray.cgColor
field.placeholder = "Password..."
field.leftView = UIView(frame: CGRect(x: 0, y: 0, width: 5, height: 0))
field.leftViewMode = .always
field.backgroundColor = .white
field.isSecureTextEntry = true
field.textAlignment = .left
field.keyboardType = .default
field.translatesAutoresizingMaskIntoConstraints = false
return field
}()
private let registerButton: UIButton = {
let button = UIButton()
button.setTitle("Create Account", for: .normal)
button.backgroundColor = .systemGreen
button.setTitleColor(.white, for: .normal)
button.layer.cornerRadius = 12
button.layer.masksToBounds = true
button.titleLabel?.font = .systemFont(ofSize: 20, weight: .bold)
button.translatesAutoresizingMaskIntoConstraints = false
return button
}()
override func viewDidLoad() {
super.viewDidLoad()
title = "Create Account"
view.backgroundColor = .white
view.addSubview(scrollView)
scrollView.addSubview(scrollInnerView)
scrollInnerView.addSubview(profilePic)
scrollInnerView.addSubview(usernameField)
scrollInnerView.addSubview(emailField)
scrollInnerView.addSubview(passwordField)
scrollInnerView.addSubview(registerButton)
usernameField.delegate = self
emailField.delegate = self
passwordField.delegate = self
profilePic.isUserInteractionEnabled = true
registerButton.addTarget(self,
action: #selector(registerButtonTapped),
for: .touchUpInside)
setUpKeyboard()
setUpConstraints()
}
private func setUpConstraints() {
// Scroll View Constraints
scrollView.topAnchor.constraint(equalTo: view.safeAreaLayoutGuide.topAnchor).isActive = true
scrollView.leadingAnchor.constraint(equalTo: view.leadingAnchor).isActive = true
scrollView.trailingAnchor.constraint(equalTo: view.trailingAnchor).isActive = true
scrollView.bottomAnchor.constraint(equalTo: view.safeAreaLayoutGuide.bottomAnchor).isActive = true
// Scroll Inner View Constraints
scrollInnerView.topAnchor.constraint(equalTo: scrollView.topAnchor).isActive = true
scrollInnerView.leadingAnchor.constraint(equalTo: scrollView.leadingAnchor).isActive = true
scrollInnerView.trailingAnchor.constraint(equalTo: scrollView.trailingAnchor).isActive = true
scrollInnerView.bottomAnchor.constraint(equalTo: scrollView.bottomAnchor).isActive = true
scrollInnerView.widthAnchor.constraint(equalTo: scrollView.widthAnchor).isActive = true
scrollInnerView.heightAnchor.constraint(equalTo: scrollView.heightAnchor, constant: 1).isActive = true
// Profile Picture Constraints
profilePic.widthAnchor.constraint(equalTo: scrollInnerView.widthAnchor, multiplier: 1/3).isActive = true
profilePic.heightAnchor.constraint(equalTo: scrollInnerView.widthAnchor, multiplier: 1/3).isActive = true
profilePic.centerXAnchor.constraint(equalTo: scrollInnerView.centerXAnchor).isActive = true
profilePic.topAnchor.constraint(equalTo: scrollInnerView.topAnchor, constant: 10).isActive = true
// User Name Field Constraints
usernameField.widthAnchor.constraint(equalTo: scrollInnerView.widthAnchor, constant: -60).isActive = true
usernameField.heightAnchor.constraint(equalToConstant: 45).isActive = true
usernameField.topAnchor.constraint(equalTo: profilePic.bottomAnchor, constant: 10).isActive = true
usernameField.centerXAnchor.constraint(equalTo: profilePic.centerXAnchor).isActive = true
// Email Field Constraints
emailField.widthAnchor.constraint(equalTo: usernameField.widthAnchor).isActive = true
emailField.heightAnchor.constraint(equalTo: usernameField.heightAnchor).isActive = true
emailField.topAnchor.constraint(equalTo: usernameField.bottomAnchor, constant: 10).isActive = true
emailField.centerXAnchor.constraint(equalTo: usernameField.centerXAnchor).isActive = true
// Password Field Constraints
passwordField.widthAnchor.constraint(equalTo: emailField.widthAnchor).isActive = true
passwordField.heightAnchor.constraint(equalTo: emailField.heightAnchor).isActive = true
passwordField.topAnchor.constraint(equalTo: emailField.bottomAnchor, constant: 10).isActive = true
passwordField.centerXAnchor.constraint(equalTo: emailField.centerXAnchor).isActive = true
// Register Button Constraints
registerButton.widthAnchor.constraint(equalTo: passwordField.widthAnchor).isActive = true
registerButton.heightAnchor.constraint(equalTo: passwordField.heightAnchor).isActive = true
registerButton.topAnchor.constraint(equalTo: passwordField.bottomAnchor, constant: 20).isActive = true
registerButton.centerXAnchor.constraint(equalTo: passwordField.centerXAnchor).isActive = true
}
private func setUpKeyboard() {
NotificationCenter.default.addObserver(self, selector: #selector(keyboardWillShowNotification), name: UIResponder.keyboardWillShowNotification, object: nil)
NotificationCenter.default.addObserver(self, selector: #selector(keyboardWillHideNotification), name: UIResponder.keyboardWillHideNotification, object: nil)
}
@objc private func keyboardWillShowNotification(_ notification: NSNotification) {
guard let keyboardSize = (notification.userInfo?[UIResponder.keyboardFrameEndUserInfoKey] as? NSValue)?.cgRectValue
else {
return
}
print(keyboardSize.minY)
print(registerButton.frame.maxY)
}
}
因为键盘边框和按键边框在两个不同的坐标系下。你不能直接比较它们。在比较它们之前，您需要 convert 按钮框架到 window 坐标。否则 将键盘框架转换 到按钮框架坐标（按钮的父视图）。
实际上我通常做的是将键盘框架转换为目标视图的内部坐标，并将其与目标视图的边界.例如：
// n is the notification
let d = n.userInfo!
var r = d[UIResponder.keyboardFrameEndUserInfoKey] as! CGRect
r = self.slidingView.convert(r, from:nil) // <- this is the key move!
let h = self.slidingView.bounds.intersection(r).height
这告诉我键盘是否会覆盖滑动视图，如果是，覆盖多少。