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。
参考以下内容
import UIKit
@available(tvOS, unavailable)
public class KeyboardLayoutConstraint: NSLayoutConstraint {
private var offset : CGFloat = 0
private var keyboardVisibleHeight : CGFloat = 0
@available(tvOS, unavailable)
override public func awakeFromNib() {
super.awakeFromNib()
offset = constant
NotificationCenter.default.addObserver(self, selector: #selector(KeyboardLayoutConstraint.keyboardWillShowNotification(_:)), name: NSNotification.Name.UIKeyboardWillShow, object: nil)
NotificationCenter.default.addObserver(self, selector: #selector(KeyboardLayoutConstraint.keyboardWillHideNotification(_:)), name: NSNotification.Name.UIKeyboardWillHide, object: nil)
}
deinit {
NotificationCenter.default.removeObserver(self)
}
// MARK: Notification
@objc func keyboardWillShowNotification(_ notification: Notification) {
if let userInfo = notification.userInfo {
if let frameValue = userInfo[UIKeyboardFrameEndUserInfoKey] as? NSValue {
let frame = frameValue.cgRectValue
keyboardVisibleHeight = frame.size.height
}
self.updateConstant()
switch (userInfo[UIKeyboardAnimationDurationUserInfoKey] as? NSNumber, userInfo[UIKeyboardAnimationCurveUserInfoKey] as? NSNumber) {
case let (.some(duration), .some(curve)):
let options = UIViewAnimationOptions(rawValue: curve.uintValue)
UIView.animate(
withDuration: TimeInterval(duration.doubleValue),
delay: 0,
options: options,
animations: {
UIApplication.shared.keyWindow?.layoutIfNeeded()
return
}, completion: { finished in
})
default:
break
}
}
}
@objc func keyboardWillHideNotification(_ notification: NSNotification) {
keyboardVisibleHeight = 0
self.updateConstant()
if let userInfo = notification.userInfo {
switch (userInfo[UIKeyboardAnimationDurationUserInfoKey] as? NSNumber, userInfo[UIKeyboardAnimationCurveUserInfoKey] as? NSNumber) {
case let (.some(duration), .some(curve)):
let options = UIViewAnimationOptions(rawValue: curve.uintValue)
UIView.animate(
withDuration: TimeInterval(duration.doubleValue),
delay: 0,
options: options,
animations: {
UIApplication.shared.keyWindow?.layoutIfNeeded()
return
}, completion: { finished in
})
default:
break
}
}
}
func updateConstant() {
self.constant = offset + keyboardVisibleHeight
}
}
对于Swift程序员:
这将为您完成所有工作,只需将这些放在视图控制器类中,并将UITextFieldDelegate实现到视图控制器,并将textField的委托设置为self
textField.delegate = self // Setting delegate of your UITextField to self
实现委托回调方法:
func textFieldDidBeginEditing(textField: UITextField) {
animateViewMoving(true, moveValue: 100)
}
func textFieldDidEndEditing(textField: UITextField) {
animateViewMoving(false, moveValue: 100)
}
// Lifting the view up
func animateViewMoving (up:Bool, moveValue :CGFloat){
let movementDuration:NSTimeInterval = 0.3
let movement:CGFloat = ( up ? -moveValue : moveValue)
UIView.beginAnimations( "animateView", context: nil)
UIView.setAnimationBeginsFromCurrentState(true)
UIView.setAnimationDuration(movementDuration )
self.view.frame = CGRectOffset(self.view.frame, 0, movement)
UIView.commitAnimations()
}
对于Swift 4、4.2、5:改变
self.view.frame = CGRectOffset(self.view.frame, 0, movement)
to
self.view.frame = self.view.frame.offsetBy(dx: 0, dy: movement)
关于此实现的最后一点注意事项:如果在显示键盘时将另一个视图控制器推到堆栈上,这将产生一个错误,其中视图返回到其中心框架,但键盘偏移未重置。例如,您的键盘是nameField的第一个响应者,但随后您按下一个按钮,将帮助视图控制器推到堆栈上。若要修复偏移错误,请确保在离开视图控制器之前调用nameField.issentFirstResponder(),确保同时调用textFieldDidEndEditing委托方法。我在viewWillDisappear方法中这样做。
实际上,最好只使用苹果的实现,正如文档中所提供的那样。然而,他们提供的代码是错误的。将keyboardWasShow:注释下方的部分替换为以下内容:
NSDictionary* info = [aNotification userInfo];
CGRect keyPadFrame=[[UIApplication sharedApplication].keyWindow convertRect:[[info objectForKey:UIKeyboardFrameBeginUserInfoKey] CGRectValue] fromView:self.view];
CGSize kbSize =keyPadFrame.size;
CGRect activeRect=[self.view convertRect:activeField.frame fromView:activeField.superview];
CGRect aRect = self.view.bounds;
aRect.size.height -= (kbSize.height);
CGPoint origin = activeRect.origin;
origin.y -= backScrollView.contentOffset.y;
if (!CGRectContainsPoint(aRect, origin)) {
CGPoint scrollPoint = CGPointMake(0.0,CGRectGetMaxY(activeRect)-(aRect.size.height));
[backScrollView setContentOffset:scrollPoint animated:YES];
}
苹果代码存在以下问题:(1) 他们总是计算该点是否在视图的框架内,但它是一个ScrollView,因此它可能已经滚动,您需要考虑该偏移:
origin.y -= scrollView.contentOffset.y
(2) 他们按键盘的高度移动contentOffset,但我们希望相反(我们希望按屏幕上可见的高度而不是不可见的高度移动contentOffset):
activeField.frame.origin.y-(aRect.size.height)
它很简单:-
在TextFieldDidBegginEditing中:-
self.view.frame=CGRectMake(self.view.frame.origin.x, self.view.frame.origin.y-150, self.view.frame.size.width, self.view.frame.size.height);
在TextFieldShouldEndEditing中:-
self.view.frame=CGRectMake(self.view.frame.origin.x, self.view.frame.origin.y+150, self.view.frame.size.width, self.view.frame.size.height);