使用iOS SDK：
我有一个带UITextFields的UIView，可以启动键盘。我需要它能够：
启动键盘后，允许滚动UIScrollView的内容以查看其他文本字段自动“跳转”（通过向上滚动）或缩短
我知道我需要一个UIScrollView。我已经尝试将UIView的类更改为UIScrollView，但仍然无法上下滚动文本框。
我需要UIView和UIScrollView吗？一个在另一个里面吗？
要自动滚动到活动文本字段，需要执行哪些操作？
理想情况下，尽可能多的组件设置将在Interface Builder中完成。我只想编写需要的代码。
注意：我使用的UIView（或UIScrollView）是由一个选项卡（UITabBar）启动的，它需要正常工作。
我正在添加滚动条，只为键盘出现时使用。尽管不需要它，但我觉得它提供了一个更好的界面，例如，用户可以滚动和更改文本框。
当键盘上下移动时，我可以改变UIScrollView的框架大小。我只是在使用：
-(void)textFieldDidBeginEditing:(UITextField *)textField {
//Keyboard becomes visible
scrollView.frame = CGRectMake(scrollView.frame.origin.x,
scrollView.frame.origin.y,
scrollView.frame.size.width,
scrollView.frame.size.height - 215 + 50); // Resize
}
-(void)textFieldDidEndEditing:(UITextField *)textField {
// Keyboard will hide
scrollView.frame = CGRectMake(scrollView.frame.origin.x,
scrollView.frame.origin.y,
scrollView.frame.size.width,
scrollView.frame.size.height + 215 - 50); // Resize
}
然而，这不会自动“向上移动”或将可见区域中的下部文本字段居中，这是我真正想要的。
Swift 3.0版本的苹果键盘管理代码如下：以下代码中使用的FloatingTF是iOS中基于材质设计的文本字段。
import UIKit
class SignupViewController: UIViewController, UITextFieldDelegate {
//MARK: - IBOutlet:
@IBOutlet weak var emailTF: FloatingTF!
@IBOutlet weak var passwordTF: FloatingTF!
@IBOutlet weak var dobTF: FloatingTF!
@IBOutlet weak var scrollView: UIScrollView!
//MARK: - Variable:
var activeTextField: UITextField!
//MARK: - ViewController Lifecycle:
override func viewDidLoad() {
super.viewDidLoad()
emailTF.delegate = self
passwordTF.delegate = self
dobTF.delegate = self
}
override func viewWillAppear(_ animated: Bool) {
super.viewWillAppear(animated)
registerKeyboardNotifications()
}
override func viewWillDisappear(_ animated: Bool) {
super.viewWillDisappear(animated)
deRegisterKeyboardNotifications()
}
//MARK: - Keyboard notification observer Methods
fileprivate func registerKeyboardNotifications() {
NotificationCenter.default.addObserver(self, selector: #selector(SignupViewController.keyboardWillShow), name: NSNotification.Name.UIKeyboardWillShow, object: nil)
NotificationCenter.default.addObserver(self, selector: #selector(SignupViewController.keyboardWillHide), name: NSNotification.Name.UIKeyboardWillHide, object: nil)
}
fileprivate func deRegisterKeyboardNotifications() {
NotificationCenter.default.removeObserver(self, name: .UIKeyboardWillShow, object: self.view.window)
NotificationCenter.default.removeObserver(self, name: .UIKeyboardDidHide, object: self.view.window)
}
func keyboardWillShow(notification: NSNotification) {
let info: NSDictionary = notification.userInfo! as NSDictionary
let value: NSValue = info.value(forKey: UIKeyboardFrameBeginUserInfoKey) as! NSValue
let keyboardSize: CGSize = value.cgRectValue.size
let contentInsets: UIEdgeInsets = UIEdgeInsetsMake(0.0, 0.0, keyboardSize.height, 0.0)
scrollView.contentInset = contentInsets
scrollView.scrollIndicatorInsets = contentInsets
// If active text field is hidden by keyboard, scroll it so it's visible
// Your app might not need or want this behavior.
var aRect: CGRect = self.view.frame
aRect.size.height -= keyboardSize.height
let activeTextFieldRect: CGRect? = activeTextField?.frame
let activeTextFieldOrigin: CGPoint? = activeTextFieldRect?.origin
if (!aRect.contains(activeTextFieldOrigin!)) {
scrollView.scrollRectToVisible(activeTextFieldRect!, animated:true)
} }
func keyboardWillHide(notification: NSNotification) {
let contentInsets: UIEdgeInsets = .zero
scrollView.contentInset = contentInsets
scrollView.scrollIndicatorInsets = contentInsets
}
//MARK: - UITextField Delegate Methods
func textFieldShouldReturn(_ textField: UITextField) -> Bool {
if textField == emailTF {
passwordTF.becomeFirstResponder()
}
else if textField == passwordTF {
dobTF.becomeFirstResponder()
}
else {
self.view.endEditing(true)
}
return true
}
func textFieldDidBeginEditing(_ textField: UITextField) {
activeTextField = textField
scrollView.isScrollEnabled = true
}
func textFieldDidEndEditing(_ textField: UITextField) {
activeTextField = nil
scrollView.isScrollEnabled = false
}
}
这是我为特定布局想出的破解方案。此解决方案与Matt Gallagher的解决方案相似，即将一个部分滚动到视图中。我还是iPhone开发的新手，不熟悉布局的工作原理。因此，这个黑客。
我的实现需要支持在字段中单击时滚动，以及用户在键盘上选择下一个时滚动。
我有一个UIView，身高775。控件基本上以3人一组的方式分布在一个大的空间中。我最终得到了以下IB布局。
UIView -> UIScrollView -> [UI Components]
黑客来了
我将UIScrollView的高度设置为比实际布局（1250）大500个单位。然后，我创建了一个数组，其中包含我需要滚动到的绝对位置，以及一个基于IB标记号获取它们的简单函数。
static NSInteger stepRange[] = {
0, 0, 0, 0, 0, 0, 0, 0, 0, 140, 140, 140, 140, 140, 410
};
NSInteger getScrollPos(NSInteger i) {
if (i < TXT_FIELD_INDEX_MIN || i > TXT_FIELD_INDEX_MAX) {
return 0 ;
return stepRange[i] ;
}
现在，您需要做的就是在textFieldDidBeginEditing和textFieldShouldReturn中使用以下两行代码（如果要创建下一个字段导航，则使用后者）
CGPoint point = CGPointMake(0, getScrollPos(textField.tag)) ;
[self.scrollView setContentOffset:point animated:YES] ;
一个例子。
- (void) textFieldDidBeginEditing:(UITextField *)textField
{
CGPoint point = CGPointMake(0, getScrollPos(textField.tag)) ;
[self.scrollView setContentOffset:point animated:YES] ;
}
- (BOOL)textFieldShouldReturn:(UITextField *)textField {
NSInteger nextTag = textField.tag + 1;
UIResponder* nextResponder = [textField.superview viewWithTag:nextTag];
if (nextResponder) {
[nextResponder becomeFirstResponder];
CGPoint point = CGPointMake(0, getScrollPos(nextTag)) ;
[self.scrollView setContentOffset:point animated:YES] ;
}
else{
[textField resignFirstResponder];
}
return YES ;
}
此方法不像其他方法那样“向后滚动”。这不是必需的。同样，这是一个相当“高大”的UIView，我没有时间学习内部布局引擎。
有很多答案可以告诉我们这个方法。我采取了相同的方法，但实施效果不佳。
这是基本想法。我修改了keyboardWasShown方法。
{
// Obtain keyboard Info
NSDictionary* info = [notification userInfo];
CGRect keyboardRect = [[info objectForKey:UIKeyboardFrameBeginUserInfoKey] CGRectValue];
keyboardRect = [self.view convertRect:keyboardRect fromView:nil];
// Obtain ScrollView Info w.r.t. top View
CGRect scrollViewRect = [self.view convertRect:self.scrollView.frame fromView:nil];
// Depending upon your screen Ui, Scroll View's bottom edge might be at some offset from screen's bottom
// Calculate the exact offset
int scrollViewBottomOffset = self.view.frame.size.height - (scrollViewRect.origin.y + scrollViewRect.size.height);
int heightToBeAdjusted = keyboardRect.size.height - scrollViewBottomOffset;
// We may also need to consider the Insets if already present with ScrollView. Let's keep it simple for now
// But we should store these, so that we can restore the Insets when Keyboard is gone
// origInsets = self.scrollView.contentInset;
// Set the new Insets for ScrollView
UIEdgeInsets contentInsets = UIEdgeInsetsMake(0.0, 0.0, heightToBeAdjusted, 0.0);
self.scrollView.contentInset = contentInsets;
self.scrollView.scrollIndicatorInsets = contentInsets;
// Visible frame (not overlapped by Keyboard)
CGRect visibleFrame = self.view.frame;
visibleFrame.size.height -= keyboardRect.size.height;
// Get the Rect for Textfield w.r.t self.view
CGRect activeFieldFrame = self.activeField.frame;
activeFieldFrame = [self.view convertRect:activeFieldFrame fromView:self.scrollView];
// Check if the TextField is Visible or not
if (!CGRectContainsRect(visibleFrame, activeFieldFrame) ) {
// Scroll to make it visible but for scrolling use the activeField frame w.r.t. to scroll View
[self.scrollView scrollRectToVisible:self.activeField.frame animated:YES];
}
}
并添加此方法来初始化activeField
- (IBAction)textFieldDidBeginEditing:(UITextField *)sender
{
self.activeField = sender;
}
使用ViewModifier快速切换UI
可以使用SwiftUI的ViewModifier。这要简单得多。
import SwiftUI
import Combine
struct KeyboardAwareModifier: ViewModifier {
@State private var keyboardHeight: CGFloat = 0
private var keyboardHeightPublisher: AnyPublisher<CGFloat, Never> {
Publishers.Merge(
NotificationCenter.default
.publisher(for: UIResponder.keyboardWillShowNotification)
.compactMap { $0.userInfo?[UIResponder.keyboardFrameEndUserInfoKey] as? NSValue }
.map { $0.cgRectValue.height },
NotificationCenter.default
.publisher(for: UIResponder.keyboardWillHideNotification)
.map { _ in CGFloat(0) }
).eraseToAnyPublisher()
}
func body(content: Content) -> some View {
content
.padding(.bottom, keyboardHeight)
.onReceive(keyboardHeightPublisher) { self.keyboardHeight = $0 }
}
}
extension View {
func KeyboardAwarePadding() -> some View {
ModifiedContent(content: self, modifier: KeyboardAwareModifier())
}
}
在你看来
struct SomeView: View {
@State private var someText: String = ""
var body: some View {
VStack {
Spacer()
TextField("some text", text: $someText)
}.KeyboardAwarePadding()
}
}
KeyboardAwarePadding（）将自动为视图添加填充。它更优雅。
