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
}
}
我对UIScrollView由多个UITextField组成也有很多问题，其中一个或多个在编辑时会被键盘遮挡。
如果UIScrollView滚动不正确，请考虑以下几点。
1） 确保contentSize大于UIScrollView框架大小。理解UIScrollViews的方法是UIScrollView就像一个查看contentSize中定义的内容的窗口。因此，如果要让UIScrollview滚动到任何位置，contentSize必须大于UIScrollview。否则，不需要滚动，因为contentSize中定义的所有内容都已可见。BTW，默认contentSize=CGSizeZero。
2） 既然您已经了解到UIScrollView实际上是一个“内容”窗口，那么确保键盘不会遮挡UIScroll View的查看“窗口”的方法就是调整UIScrollView的大小，这样当键盘出现时，UIScrollView窗口的大小就等于UIScrollviewframe.size.height减去键盘的高度。这将确保您的窗口仅是那个小的可视区域。
3） 这里有一个陷阱：当我第一次实现这一点时，我想我必须获得编辑文本字段的CGRect，并调用UIScrollView的scrollRecToVisible方法。我通过调用scrollRecToVisible方法实现了UITextFieldDelegate方法textFieldDidBeginEditing。这实际上产生了一个奇怪的副作用，即滚动会将UITextField捕捉到位。在很长一段时间里，我都搞不清那是什么。然后我注释了textFieldDidBegginEditingDelegate方法，这一切都奏效了！！(???). 事实证明，我相信UIScrollView实际上隐式地将当前编辑的UITextField带入可视窗口。我对UITextFieldDelegate方法的实现以及随后对scrollRecToVisible的调用是多余的，这是产生奇怪副作用的原因。
因此，当键盘出现时，以下是在UIScrollView中正确滚动UITextField的步骤。
// Implement viewDidLoad to do additional setup after loading the view, typically from a nib.
- (void)viewDidLoad
{
[super viewDidLoad];
// register for keyboard notifications
[[NSNotificationCenter defaultCenter] addObserver:self
selector:@selector(keyboardWillShow:)
name:UIKeyboardWillShowNotification
object:self.view.window];
// register for keyboard notifications
[[NSNotificationCenter defaultCenter] addObserver:self
selector:@selector(keyboardWillHide:)
name:UIKeyboardWillHideNotification
object:self.view.window];
keyboardIsShown = NO;
//make contentSize bigger than your scrollSize (you will need to figure out for your own use case)
CGSize scrollContentSize = CGSizeMake(320, 345);
self.scrollView.contentSize = scrollContentSize;
}
- (void)keyboardWillHide:(NSNotification *)n
{
NSDictionary* userInfo = [n userInfo];
// get the size of the keyboard
CGSize keyboardSize = [[userInfo objectForKey:UIKeyboardFrameEndUserInfoKey] CGRectValue].size;
// resize the scrollview
CGRect viewFrame = self.scrollView.frame;
// I'm also subtracting a constant kTabBarHeight because my UIScrollView was offset by the UITabBar so really only the portion of the keyboard that is leftover pass the UITabBar is obscuring my UIScrollView.
viewFrame.size.height += (keyboardSize.height - kTabBarHeight);
[UIView beginAnimations:nil context:NULL];
[UIView setAnimationBeginsFromCurrentState:YES];
[self.scrollView setFrame:viewFrame];
[UIView commitAnimations];
keyboardIsShown = NO;
}
- (void)keyboardWillShow:(NSNotification *)n
{
// This is an ivar I'm using to ensure that we do not do the frame size adjustment on the `UIScrollView` if the keyboard is already shown. This can happen if the user, after fixing editing a `UITextField`, scrolls the resized `UIScrollView` to another `UITextField` and attempts to edit the next `UITextField`. If we were to resize the `UIScrollView` again, it would be disastrous. NOTE: The keyboard notification will fire even when the keyboard is already shown.
if (keyboardIsShown) {
return;
}
NSDictionary* userInfo = [n userInfo];
// get the size of the keyboard
CGSize keyboardSize = [[userInfo objectForKey:UIKeyboardFrameEndUserInfoKey] CGRectValue].size;
// resize the noteView
CGRect viewFrame = self.scrollView.frame;
// I'm also subtracting a constant kTabBarHeight because my UIScrollView was offset by the UITabBar so really only the portion of the keyboard that is leftover pass the UITabBar is obscuring my UIScrollView.
viewFrame.size.height -= (keyboardSize.height - kTabBarHeight);
[UIView beginAnimations:nil context:NULL];
[UIView setAnimationBeginsFromCurrentState:YES];
[self.scrollView setFrame:viewFrame];
[UIView commitAnimations];
keyboardIsShown = YES;
}
在viewDidLoad上注册键盘通知在viewDidUnload中注销键盘nofitions确保contentSize设置为大于UIScrollView at viewDidLoad当有键盘时，缩小UIScrollView当键盘离开时，恢复UIScrollView。使用ivar来检测键盘是否已经显示在屏幕上，因为每次UITextField选项卡时都会发送键盘通知，即使键盘已经存在，以避免在UIScrollView已经缩小时缩小它
需要注意的一点是，当您单击另一个UITextField时，即使键盘已经在屏幕上，UIKeyboardWillShowNotification也会启动。当键盘已经在屏幕上时，我使用ivar来避免调整UIScrollView的大小。当键盘已经存在时，不小心调整UIScrollView的大小将是灾难性的！
希望这段代码能让你们中的一些人省去很多麻烦。
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
}
}
我在这里没有看到这种可能性，所以我添加了它，因为我尝试了答案中的方法，但几个小时后发现在iOS6/7中的XCode 5中有一种更简单的方法：使用NSLayoutConstraints。
请参见：自动布局约束-键盘
这是我的代码：
.m文件：
// Called when the UIKeyboardWillShowNotification is sent.
- (void)keyboardWillBeShown:(NSNotification*)aNotification
{
NSLog(@"keyboardWillBeShown:");
[self.PhoneNumberLabelOutlet setHidden:TRUE];
CGFloat heightOfLabel = self.PhoneNumberLabelOutlet.frame.size.height;
for( NSLayoutConstraint* thisConstraint in self.topElementsVerticalDistanceFromTopLayoutConstraint ) {
thisConstraint.constant -= heightOfLabel;
}
NSDictionary* info = [aNotification userInfo];
CGSize kbSize = [[info objectForKey:UIKeyboardFrameBeginUserInfoKey] CGRectValue].size;
CGFloat oldConstant = [self.SignInYConstraint constant];
self.SignInYConstraint.constant = oldConstant + kbSize.height;
[self.view setNeedsUpdateConstraints];
NSTimeInterval duration = [[info objectForKey:UIKeyboardAnimationDurationUserInfoKey] doubleValue];
[UIView animateWithDuration:duration animations:^{
[self.view layoutIfNeeded];
}];
}
.h文件：
#import <UIKit/UIKit.h>
@interface SignInViewController : UIViewController {
UITextField* _activeField;
}
- (void)signInCallback:(NSObject*)object;
@property (weak, nonatomic) IBOutlet UILabel *PhoneNumberLabelOutlet;
@property (weak, nonatomic) IBOutlet UIActivityIndicatorView *ActivityIndicatorOutlet;
@property (weak, nonatomic) IBOutlet UITextField *UserIDTextfieldOutlet;
@property (weak, nonatomic) IBOutlet UITextField *PasswordTextfieldOutlet;
@property (weak, nonatomic) IBOutlet UIButton *SignInButton;
@property (weak, nonatomic) IBOutlet NSLayoutConstraint *SignInYConstraint;
@property (strong, nonatomic) IBOutletCollection(NSLayoutConstraint) NSArray *topElementsVerticalDistanceFromTopLayoutConstraint;
@end
