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。
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;
}
添加我的5美分：）
我总是喜欢使用tableView作为inputTextField或scrollView。结合通知，您可以轻松管理此类行为。（注意，如果您在tableView中使用静态单元格，则这种行为将自动为您管理。）
// MARK: - Notifications
fileprivate func registerNotificaitions() {
NotificationCenter.default.addObserver(self, selector: #selector(AddRemoteControlViewController.keyboardWillAppear(_:)),
name: NSNotification.Name.UIKeyboardWillShow, object: nil)
NotificationCenter.default.addObserver(self, selector: #selector(AddRemoteControlViewController.keyboardWillDisappear),
name: NSNotification.Name.UIKeyboardWillHide, object: nil)
}
fileprivate func unregisterNotifications() {
NotificationCenter.default.removeObserver(self)
}
@objc fileprivate func keyboardWillAppear(_ notification: Notification) {
if let keyboardHeight = (notification.userInfo?[UIKeyboardFrameEndUserInfoKey] as? NSValue)?.cgRectValue.height {
view.layoutIfNeeded()
UIView.animate(withDuration: 0.3, animations: {
let heightInset = keyboardHeight - self.addDeviceButton.frame.height
self.tableView.contentInset = UIEdgeInsets(top: 0, left: 0, bottom: heightInset, right: 0)
self.view.layoutIfNeeded()
}, completion: nil)
}
}
@objc fileprivate func keyboardWillDisappear() {
view.layoutIfNeeded()
UIView.animate(withDuration: 0.3, animations: {
self.tableView.contentInset = UIEdgeInsets.zero
self.view.layoutIfNeeded()
}, completion: nil)
}
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)
}
}
