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。
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。
我发现这是最好的解决方案,请遵循以下代码:
将以下内容附加到垂直空间-底部布局指南-文本字段约束。
@property (weak, nonatomic) IBOutlet NSLayoutConstraint *textViewBottomConst;
第二,为键盘通知添加观察员。
- (void)observeKeyboard {
[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(keyboardWillShow:) name:UIKeyboardWillShowNotification object:nil];
[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(keyboardWillHide:) name:UIKeyboardWillHideNotification object:nil];
}
将此添加到您的视图DidLoad
[self observeKeyboard];
最后,处理键盘更改的方法。
- (void)keyboardWillShow:(NSNotification *)notification {
//THIS WILL MAKE SURE KEYBOARD DOESNT JUMP WHEN OPENING QUICKTYPE/EMOJI OR OTHER KEYBOARDS.
kbHeight = 0;
height = 0;
self.textViewBottomConst.constant = height;
self.btnViewBottomConst.constant = height;
NSDictionary *info = [notification userInfo];
NSValue *kbFrame = [info objectForKey:UIKeyboardFrameEndUserInfoKey];
NSTimeInterval animationDuration = [[info objectForKey:UIKeyboardAnimationDurationUserInfoKey] doubleValue];
CGRect keyboardFrame = [kbFrame CGRectValue];
CGRect finalKeyboardFrame = [self.view convertRect:keyboardFrame fromView:self.view.window];
int kbHeight = finalKeyboardFrame.size.height;
int height = kbHeight + self.textViewBottomConst.constant;
self.textViewBottomConst.constant = height;
[UIView animateWithDuration:animationDuration animations:^{
[self.view layoutIfNeeded];
}];
}
- (void)keyboardWillHide:(NSNotification *)notification {
NSDictionary *info = [notification userInfo];
NSTimeInterval animationDuration = [[info objectForKey:UIKeyboardAnimationDurationUserInfoKey] doubleValue];
self.textViewBottomConst.constant = 10;
[UIView animateWithDuration:animationDuration animations:^{
[self.view layoutIfNeeded];
}];
}
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