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。
我想延长@sumanthkodi的回答。
正如一些人所说，他的方法在较新的实现中不起作用，因为当您使用约束时，UIView无法移动。
我编辑了如下代码（并移植到Swift 2.0），希望它能帮助一些人：
1） 参照要向上移动的视图的垂直约束：
@IBOutlet var viewConstraint: NSLayoutConstraint!
确保在脚本中使用约束引用此变量。
2） 添加委托并实现侦听器。这是与之前相同的实现：
class YourViewController: UIViewController, UITextFieldDelegate {
...
func textFieldDidBeginEditing(textField: UITextField) {
animateTextField(textField, up: true)
}
func textFieldDidEndEditing(textField: UITextField) {
animateTextField(textField, up: false)
}
...
}
3） 将动画方法animateTextField添加到YourViewController类。根据需要设置临时约束值。
func animateTextField(textfield: UITextField, up: Bool) {
let originalConstraint = 50
let temporaryConstraint = 0
let movementDuration = 0.3
let constraint = CGFloat(up ? temporaryConstraint : originalConstraint)
containerViewConstraint.constant = constraint
UIView.animateWithDuration(movementDuration) {
self.view.layoutIfNeeded()
}
}
注意：此答案假设您的textField位于scrollView中。
我更喜欢使用scrollContentInset和scrollContentOffset来处理这个问题，而不是干扰视图的框架。
首先让我们听听键盘通知
//call this from viewWillAppear
-(void)addKeyboardNotifications
{
[[NSNotificationCenter defaultCenter] addObserver:self
selector:@selector(keyboardWillShow:)
name:UIKeyboardWillShowNotification
object:nil];
[[NSNotificationCenter defaultCenter] addObserver:self
selector:@selector(keyboardWillHide:)
name:UIKeyboardWillHideNotification
object:nil];
}
//call this from viewWillDisappear
-(void)removeKeyboardNotifications{
[[NSNotificationCenter default
Center] removeObserver:self name:UIKeyboardWillShowNotification object:nil];
[[NSNotificationCenter defaultCenter] removeObserver:self name:UIKeyboardWillHideNotification object:nil];
}
下一步是保留表示当前第一响应者的属性（当前具有键盘的UITextfield/UUITextVIew）。
我们使用委托方法来设置此属性。如果您正在使用另一个组件，则需要类似的组件。
请注意，对于textfield，我们在didBegginEditing中设置它，而对于textView，我们在shouldBeginEditing中将其设置。这是因为出于某种原因，在UIKeyboardWillShowNotification之后调用textViewDidBegginEditing。
-(BOOL)textViewShouldBeginEditing:(UITextView * )textView{
self.currentFirstResponder = textView;
return YES;
}
-(void)textFieldDidBeginEditing:(UITextField *)textField{
self.currentFirstResponder = textField;
}
最后，这里是魔术
- (void)keyboardWillShow:(NSNotification*)aNotification{
NSDictionary* info = [aNotification userInfo];
CGRect kbFrame = [[info objectForKey:UIKeyboardFrameEndUserInfoKey] CGRectValue];
/*if currentFirstResponder is overlayed by the keyboard, move it so it bottom ends where the keyboard begins*/
if(self.currentFirstResponder){
//keyboard origin in currentFirstResponderFrame
CGPoint keyboardOrigin = [self.currentFirstResponder convertPoint:kbFrame.origin fromView:nil];
float spaceBetweenFirstResponderAndKeyboard = abs(self.currentFirstResponder.frame.size.height-keyboardOrigin.y);
//only scroll the scrollview if keyboard overlays the first responder
if(spaceBetweenFirstResponderAndKeyboard>0){
//if i call setContentOffset:animate:YES it behaves differently, not sure why
[UIView animateWithDuration:0.25 animations:^{
[self.scrollView setContentOffset:CGPointMake(0,self.scrollView.contentOffset.y+spaceBetweenFirstResponderAndKeyboard)];
}];
}
}
//set bottom inset to the keyboard height so you can still scroll the whole content
UIEdgeInsets contentInsets = UIEdgeInsetsMake(0.0, 0.0, kbFrame.size.height, 0.0);
_scrollView.contentInset = contentInsets;
_scrollView.scrollIndicatorInsets = contentInsets;
}
- (void)keyboardWillHide:(NSNotification*)aNotification{
UIEdgeInsets contentInsets = UIEdgeInsetsZero;
_scrollView.contentInset = contentInsets;
_scrollView.scrollIndicatorInsets = contentInsets;
}
在textFieldDidBginEditing和textFieldDidEndEditing中调用函数[self-animateTextField:textField up:YES]，如下所示：
-(void)textFieldDidBeginEditing:(UITextField *)textField
{
[self animateTextField:textField up:YES];
}
- (void)textFieldDidEndEditing:(UITextField *)textField
{
[self animateTextField:textField up:NO];
}
-(void)animateTextField:(UITextField*)textField up:(BOOL)up
{
const int movementDistance = -130; // tweak as needed
const float movementDuration = 0.3f; // tweak as needed
int movement = (up ? movementDistance : -movementDistance);
[UIView beginAnimations: @"animateTextField" context: nil];
[UIView setAnimationBeginsFromCurrentState: YES];
[UIView setAnimationDuration: movementDuration];
self.view.frame = CGRectOffset(self.view.frame, 0, movement);
[UIView commitAnimations];
}
我希望这段代码对你有所帮助。
雨燕5
func animateTextField(textField: UITextField, up: Bool) {
let movementDistance: CGFloat = -130
let movementDuration: Double = 0.3
var movement:CGFloat = 0
if up {
movement = movementDistance
} else {
movement = -movementDistance
}
UIView.animate(withDuration: movementDuration, delay: 0, options: [.beginFromCurrentState]) {
self.view.frame = self.view.frame.offsetBy(dx: 0, dy: movement)
}
}
func textFieldDidBeginEditing(_ textField: UITextField) {
animateTextField(textField: textField, up: true)
}
func textFieldDidEndEditing(_ textField: UITextField) {
animateTextField(textField: textField, up: false)
}
对于Swift Developer，使用Swift 3，这里是回购https://github.com/jamesrochabrun/KeyboardWillShow
import UIKit
class ViewController: UIViewController {
//1 Create a view that will hold your TEXTFIELD
let textField: UITextField = {
let tf = UITextField()
tf.translatesAutoresizingMaskIntoConstraints = false
tf.layer.borderColor = UIColor.darkGray.cgColor
tf.layer.borderWidth = 3.0
return tf
}()
//2 global variable that will hold the bottom constraint on changes
var textfieldBottomAnchor: NSLayoutConstraint?
override func viewDidLoad() {
super.viewDidLoad()
//3 add the view to your controller
view.addSubview(textField)
textField.heightAnchor.constraint(equalToConstant: 80).isActive = true
textField.widthAnchor.constraint(equalToConstant: view.frame.width).isActive = true
textField.leftAnchor.constraint(equalTo: view.leftAnchor).isActive = true
textfieldBottomAnchor = textField.bottomAnchor.constraint(equalTo: view.bottomAnchor)
textfieldBottomAnchor?.isActive = true
setUpKeyBoardObservers()
}
//4 Use NSnotificationCenter to monitor the keyboard updates
func setUpKeyBoardObservers() {
NotificationCenter.default.addObserver(self, selector: #selector(handleKeyboardWillShow), name: NSNotification.Name.UIKeyboardWillShow, object: nil)
NotificationCenter.default.addObserver(self, selector: #selector(handleKeyboardWillHide), name: NSNotification.Name.UIKeyboardWillHide, object: nil)
}
//5 toggle the bottom layout global variable based on the keyboard's height
func handleKeyboardWillShow(notification: NSNotification) {
let keyboardFrame = notification.userInfo?[UIKeyboardFrameEndUserInfoKey] as? CGRect
if let keyboardFrame = keyboardFrame {
textfieldBottomAnchor?.constant = -keyboardFrame.height
}
let keyboardDuration = notification.userInfo?[UIKeyboardAnimationDurationUserInfoKey] as? Double
if let keyboardDuration = keyboardDuration {
UIView.animate(withDuration: keyboardDuration, animations: {
self.view.layoutIfNeeded()
})
}
}
func handleKeyboardWillHide(notification: NSNotification) {
textfieldBottomAnchor?.constant = 0
let keyboardDuration = notification.userInfo?[UIKeyboardAnimationDurationUserInfoKey] as? Double
if let keyboardDuration = keyboardDuration {
UIView.animate(withDuration: keyboardDuration, animations: {
self.view.layoutIfNeeded()
})
}
}
//6 remove the observers
override func viewDidDisappear(_ animated: Bool) {
super.viewDidDisappear(animated)
NotificationCenter.default.removeObserver(self)
}
}
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。
