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。
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;
}
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
雨燕5
在viewDidLoad或viewDidAppear中添加addKeyboardObserver方法。
fileprivate func addKeyboardObservers(){
NotificationCenter.default.addObserver(self, selector: #selector(keyboardWillShow), name: UIResponder.keyboardWillShowNotification, object: nil)
NotificationCenter.default.addObserver(self, selector: #selector(keyboardWillHide), name: UIResponder.keyboardWillHideNotification, object: nil)
}
fileprivate func removeKeyboardObservers(){
NotificationCenter.default.removeObserver(self, name: UIResponder.keyboardWillHideNotification, object: nil)
NotificationCenter.default.removeObserver(self, name: UIResponder.keyboardWillShowNotification, object: nil)
}
@objc fileprivate func keyboardWillHide(_ notification: Notification){
if (window == nil) {return}
guard let duration = (notification.userInfo?[UIResponder.keyboardAnimationDurationUserInfoKey] as? Double) else {return}
scrollView.contentInset.bottom = .zero
}
@objc fileprivate func keyboardWillShow(_ notification: Notification){
if (window == nil) {return}
if UIApplication.shared.applicationState != .active { return }
// keyboard height
guard let height = (notification.userInfo?[UIResponder.keyboardFrameEndUserInfoKey] as? CGRect)?.height else {return}
// keyboard present animation duration
guard let duration = (notification.userInfo?[UIResponder.keyboardAnimationDurationUserInfoKey] as? Double) else {return}
scrollView.contentInset.bottom = height
}
不要忘记删除或消失观察者
self.removeKeyboardObservers()
从以下链接下载TPKeyBoardAvoiding：https://github.com/michaeltyson/TPKeyboardAvoiding. 展开zipped文件夹，找到TPKeyboardAvoiding文件夹。选择所有.h和.m文件，并将其放到项目中。确保选中了复制项（如果需要）。将UIScrollView拖放到StoryBoard并与TPKeyboardAvoidingScrollView关联。现在，您可以在滚动视图的顶部添加UI元素。注意，即使在拖动scrollView之后，这个类也会检测UI元素的触摸。
在ViewController上：
@IBOutlet weak var usernameTextfield: UITextField!
@IBOutlet weak var passwordTextfield: UITextField!
@IBOutlet weak var loginScrollView: UIScrollView!
override func viewWillAppear(animated: Bool) {
loginScrollView.scrollEnabled = false
}
添加TextField委托。
//MARK:- TEXTFIELD METHODS
func textFieldShouldReturn(textField: UITextField) -> Bool
{
if (usernameTextfield.resignFirstResponder())
{
passwordTextfield.becomeFirstResponder()
}
textField.resignFirstResponder();
loginScrollView!.setContentOffset(CGPoint.zero, animated: true);
loginScrollView.scrollEnabled = false
return true
}
func textFieldDidBeginEditing(textField: UITextField)
{
loginScrollView.scrollEnabled = true
if (textField.tag == 1 && (device == "iPhone" || device == "iPhone Simulator" || device == "iPod touch"))
{
let scrollPoint:CGPoint = CGPointMake(0, passwordTextfield.frame.origin.y/6.4);
loginScrollView!.setContentOffset(scrollPoint, animated: true);
}
else if (textField.tag == 2 && (device == "iPhone" || device == "iPhone Simulator" || device == "iPod touch"))
{
let scrollPoint:CGPoint = CGPointMake(0, passwordTextfield.frame.origin.y/6.0);
loginScrollView!.setContentOffset(scrollPoint, animated: true);
}
}
func textFieldDidEndEditing(textField: UITextField)
{
loginScrollView!.setContentOffset(CGPointZero,animated: true);
}
