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。
如果你还在为这件事而挣扎，请阅读我的帖子
我今天提出了一个解决方案。我读过很多关于这个问题的帖子和“教程”，没有一篇在任何情况下都有效（大多数都是相互复制粘贴的）。甚至苹果官方提出的“解决方案”也不起作用，更重要的是，它在横向模式下完全不起作用。苹果公司没有给开发者们解决这样一个常见的基本问题的方法，真是可耻。非常不专业。如此惊人的框架（Cocoa）和如此严重的被低估的问题。
现在，我的解决方案是：让UIScrollView成为您的根视图，然后将所有内容放入其中。然后从这个KeyboardAwareController类子类化视图控制器（您可能需要重新定义scrollView和keyboardPadding方法）：
////键盘AwareController.h//社会病////管理员于2014年1月13日创建。//版权所有（c）2014 kuchumovn。保留所有权利。//
#import <UIKit/UIKit.h>
@interface KeyboardAwareController : UIViewController <UITextFieldDelegate>
@end
////键盘AwareController.m//社会病////管理员于2014年1月13日创建。//版权所有（c）2014 kuchumovn。保留所有权利。//
#import "KeyboardAwareController.h"
@interface KeyboardAwareController ()
@end
@implementation KeyboardAwareController
{
CGPoint scrollPositionBeforeKeyboardAdjustments;
__weak UIScrollView* scrollView;
UITextField* activeField;
}
- (id) initWithCoder: (NSCoder*) decoder
{
if (self = [super initWithCoder:decoder])
{
scrollPositionBeforeKeyboardAdjustments = CGPointZero;
}
return self;
}
- (void) viewDidLoad
{
[super viewDidLoad];
}
- (UIScrollView*) scrollView
{
return (UIScrollView*) self.view;
}
- (CGFloat) keyboardPadding
{
return 5;
}
- (void) registerForKeyboardNotifications
{
[[NSNotificationCenter defaultCenter] addObserver:self
selector:@selector(keyboardWillShow:)
name:UIKeyboardWillShowNotification object:nil];
[[NSNotificationCenter defaultCenter] addObserver:self
selector:@selector(keyboardDidShow:)
name:UIKeyboardDidShowNotification object:nil];
[[NSNotificationCenter defaultCenter] addObserver:self
selector:@selector(keyboardWillBeHidden:)
name:UIKeyboardWillHideNotification object:nil];
}
- (void) deregisterFromKeyboardNotifications
{
[[NSNotificationCenter defaultCenter] removeObserver:self
name:UIKeyboardWillShowNotification
object:nil];
[[NSNotificationCenter defaultCenter] removeObserver:self
name:UIKeyboardDidShowNotification
object:nil];
[[NSNotificationCenter defaultCenter] removeObserver:self
name:UIKeyboardWillHideNotification
object:nil];
}
- (void) viewWillAppear: (BOOL) animated
{
[super viewWillAppear:animated];
[self registerForKeyboardNotifications];
}
- (void) viewWillDisappear: (BOOL) animated
{
[self deregisterFromKeyboardNotifications];
[super viewWillDisappear:animated];
}
- (void) keyboardWillShow: (NSNotification*) notification
{
//NSLog(@"keyboardWillShow");
// force the animation from keyboardWillBeHidden: to end
scrollView.contentOffset = scrollPositionBeforeKeyboardAdjustments;
scrollPositionBeforeKeyboardAdjustments = CGPointZero;
}
// warning: i have no idea why this thing works and what does every line of this code mean
// (but it works and there is no other solution on the internets whatsoever)
// P.S. Shame on Apple for missing such a basic functionality from SDK (and many other basic features we have to hack and mess around with for days and nights)
- (void) keyboardDidShow: (NSNotification*) notification
{
//NSLog(@"keyboardDidShow");
UIWindow* window = [[[UIApplication sharedApplication] windows]objectAtIndex:0];
UIView* mainSubviewOfWindow = window.rootViewController.view;
CGRect keyboardFrameIncorrect = [[[notification userInfo] objectForKey:UIKeyboardFrameEndUserInfoKey] CGRectValue];
CGRect keyboardFrame = [mainSubviewOfWindow convertRect:keyboardFrameIncorrect fromView:window];
CGSize keyboardSize = keyboardFrame.size;
CGRect visibleFrame = CGRectMake(0, 0, 0, 0);
visibleFrame.origin = self.scrollView.contentOffset;
visibleFrame.size = self.scrollView.bounds.size;
CGFloat paddedKeyboardHeight = keyboardSize.height + self.keyboardPadding;
//NSLog(@"visibleFrame %@", NSStringFromCGRect(visibleFrame));
visibleFrame.size.height -= paddedKeyboardHeight;
//NSLog(@"visibleFrame after keyboard height %@", NSStringFromCGRect(visibleFrame));
if (CGRectContainsPoint(visibleFrame, activeField.frame.origin))
return;
scrollPositionBeforeKeyboardAdjustments = scrollView.contentOffset;
UIEdgeInsets contentInsets = UIEdgeInsetsMake(0.0, 0.0, activeField.frame.origin.y - visibleFrame.size.height + activeField.frame.size.height, 0);
contentInsets = UIEdgeInsetsMake(0.0, 0.0, paddedKeyboardHeight, 0);
self.scrollView.contentInset = contentInsets;
self.scrollView.scrollIndicatorInsets = contentInsets;
CGSize scrollContentSize = self.scrollView.bounds.size;
scrollContentSize.height += paddedKeyboardHeight;
self.scrollView.contentSize = scrollContentSize;
//NSLog(@"scrollView %@", NSStringFromCGRect(scrollView.frame));
//NSLog(@"activeField %@", NSStringFromCGRect(activeField.frame));
//[scrollView scrollRectToVisible:activeField.frame animated:YES];
CGPoint scrollPoint = CGPointMake(0.0, activeField.frame.origin.y - visibleFrame.size.height + activeField.frame.size.height);
//NSLog(@"scrollPoint %@", NSStringFromCGPoint(scrollPoint));
[self.scrollView setContentOffset:scrollPoint animated:YES];
}
- (void) keyboardWillBeHidden: (NSNotification*) notification
{
//NSLog(@"keyboardWillBeHidden");
UIEdgeInsets contentInsets = UIEdgeInsetsZero;
// this doesn't work when changing orientation while the keyboard is visible
// because when keyboardDidShow: will be called right after this method the contentOffset will still be equal to the old value
//[scrollView setContentOffset:scrollPositionBeforeKeyboardAdjustments animated:YES];
[UIView animateWithDuration:.25 animations:^
{
self.scrollView.contentInset = contentInsets;
self.scrollView.scrollIndicatorInsets = contentInsets;
// replacement for setContentOffset:animated:
self.scrollView.contentOffset = scrollPositionBeforeKeyboardAdjustments;
}];
}
- (void) textFieldDidBeginEditing: (UITextField*) textField
{
activeField = textField;
}
- (void) textFieldDidEndEditing: (UITextField*) textField
{
activeField = nil;
}
@end
如果您有任何问题，我的项目将在github上托管：https://github.com/kuchumovn/sociopathy.ios
为了更好地解释，我还拍了一张截图：
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)
}
}
