问题
I have a UISearchBar which acts as a live filter for a table view. When the keyboard is dismissed via endEditing:, the query text and the gray circular \"clear\" button remain. From here, if I tap the gray \"clear\" button the keyboard reappears as the text is cleared.
How do I prevent this? If the keyboard is not currently open I want that button to clear the text without reopening the keyboard.
There is a protocol method that gets called when I tap the clear button. But sending the UISearchBar a resignFirstResponder message doesn\'t have any effect on the keyboard.
回答1:
This is an old question and I just came across the same issue and managed to solve it the following way:
When the searchBar:textDidChange: method of the UISearchBarDelegate gets called because of the user tapping the 'clear' button, the searchBar hasn't become the first responder yet, so we can take advantage of that in order to detect when the user in fact intended to clear the search and not bring focus to the searchBar and/or do something else.
To keep track of that, we need to declare a BOOL ivar in our viewController that is also the searchBar delegate (let's call it shouldBeginEditing) and set it with an initial value of YES (supposing our viewController class is called SearchViewController):
@interface SearchViewController : UIViewController <UISearchBarDelegate> {
// all of our ivar declarations go here...
BOOL shouldBeginEditing;
....
}
...
@end
@implementation SearchViewController
...
- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil {
if ((self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil])) {
...
shouldBeginEditing = YES;
}
}
...
@end
Later on, in the UISearchBarDelegate, we implement the searchBar:textDidChange: and searchBarShouldBeginEditing: methods:
- (void)searchBar:(UISearchBar *)bar textDidChange:(NSString *)searchText {
NSLog(@"searchBar:textDidChange: isFirstResponder: %i", [self.searchBar isFirstResponder]);
if(![searchBar isFirstResponder]) {
// user tapped the 'clear' button
shouldBeginEditing = NO;
// do whatever I want to happen when the user clears the search...
}
}
- (BOOL)searchBarShouldBeginEditing:(UISearchBar *)bar {
// reset the shouldBeginEditing BOOL ivar to YES, but first take its value and use it to return it from the method call
BOOL boolToReturn = shouldBeginEditing;
shouldBeginEditing = YES;
return boolToReturn;
}
Basically, that's it.
Best
回答2:
I've found that resignFirstResponder doesn't work when textDidChange is called from a touch to the "clear button". However, using performSelection: withObject: afterDelay: seems to be an effective workaround:
- (void)searchBar:(UISearchBar *)searchBar textDidChange:(NSString *)searchText
{
if ([searchText length] == 0) {
[self performSelector:@selector(hideKeyboardWithSearchBar:) withObject:searchBar afterDelay:0];
}
}
- (void)hideKeyboardWithSearchBar:(UISearchBar *)searchBar
{
[searchBar resignFirstResponder];
}
回答3:
I found a pretty safe way to know if the clear button has been pressed, and ignore the times when the user just delete the last character of the UISearchBar. Here it is :
- (BOOL)searchBar:(UISearchBar *)searchBar shouldChangeTextInRange:(NSRange)range replacementText:(NSString *)text
{
_isRemovingTextWithBackspace = ([searchBar.text stringByReplacingCharactersInRange:range withString:text].length == 0);
return YES;
}
- (void)searchBar:(UISearchBar *)searchBar textDidChange:(NSString *)searchText
{
if (searchText.length == 0 && !_isRemovingTextWithBackspace)
{
NSLog(@"Has clicked on clear !");
}
}
Pretty simple and straightforward, isn't it :) ? The only thing to note is that if the user clicks the clear button when editing the UISearchBar's UITextField, you will have two pings, whereas you'll get only one if the user clicks it when it is not being edited.
Edit : I can't test it, but here's the swift version, as per Rotem :
var isRemovingTextWithBackspace = false
func searchBar(searchBar: UISearchBar, shouldChangeTextInRange range: NSRange, replacementText text: String) -> Bool
{
self.isRemovingTextWithBackspace = (NSString(string: searchBar.text!).stringByReplacingCharactersInRange(range, withString: text).characters.count == 0)
return true
}
func searchBar(searchBar: UISearchBar, textDidChange searchText: String)
{
if searchText.characters.count == 0 && !isRemovingTextWithBackspace
{
NSLog("Has clicked on clear !")
}
}
@Rotem's update (Swift2):
var isRemovingTextWithBackspace = false
func searchBar(searchBar: UISearchBar, shouldChangeTextInRange range: NSRange, replacementText text: String) -> Bool {
self.isRemovingTextWithBackspace = (NSString(string: searchBar.text!).stringByReplacingCharactersInRange(range, withString: text).characters.count == 0)
return true
}
func searchBar(searchBar: UISearchBar, textDidChange searchText: String) {
if searchText.characters.count == 0 && !isRemovingTextWithBackspace {
NSLog("Has clicked on clear!")
}
}
回答4:
I used a combination of @boliva's answer and also @radiospiel's answer to a different SO question:
@interface SearchViewController : UIViewController <UISearchBarDelegate> {
// all of our ivar declarations go here...
BOOL shouldBeginEditing;
....
}
...
@end
@implementation SearchViewController
...
- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil {
if ((self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil])) {
...
shouldBeginEditing = YES;
}
}
...
- (void) searchBar:(UISearchBar *)theSearchBar textDidChange:(NSString *)searchText {
// TODO - dynamically update the search results here, if we choose to do that.
if (![searchBar isFirstResponder]) {
// The user clicked the [X] button while the keyboard was hidden
shouldBeginEditing = NO;
}
else if ([searchText length] == 0) {
// The user clicked the [X] button or otherwise cleared the text.
[theSearchBar performSelector: @selector(resignFirstResponder)
withObject: nil
afterDelay: 0.1];
}
}
- (BOOL)searchBarShouldBeginEditing:(UISearchBar *)bar {
// reset the shouldBeginEditing BOOL ivar to YES, but first take its value and use it to return it from the method call
BOOL boolToReturn = shouldBeginEditing;
shouldBeginEditing = YES;
return boolToReturn;
}
@end
回答5:
Best solution from my experience is just to put a UIButton (with clear background and no text) above the system clear button and than connect an IBAction
With autolayout its just more than easy
- (IBAction)searchCancelButtonPressed:(id)sender {
[self.searchBar resignFirstResponder];
self.searchBar.text = @"";
// some of my stuff
self.model.fastSearchText = nil;
[self.model fetchData];
[self reloadTableViewAnimated:NO];
}
回答6:
Pressing the "clear" button in a UISearchBar automatically opens the keyboard even if you call searchBar.resignFirstResponder() within the textDidChange UISearchBarDelegate method.
To actually hide the keyboard when you press the "x" to clear the UISearchBar, use the following code. This way, even if textDidChange gets called while typing something in the UISearchBar, you only hide the keyboard if you delete all the text within it, weather you use the delete button or you click the "x":
extension ViewController: UISearchBarDelegate {
func searchBar(_ searchBar: UISearchBar, textDidChange searchText: String) {
if searchBar.text!.count == 0 {
DispatchQueue.main.async {
searchBar.resignFirstResponder()
}
} else {
// Code to make a request here.
}
}
}
回答7:
In your endEditing method, why don't you clear the UISearchBar and there? Since that must be where you resign first responder also, it makes sense.
回答8:
Of of the search bar delegate calls asks you to accept a change from an old value to a new one - you could detect that the new value was nil, along with the old value being not-nil, and an indicator that the user had not typed anything since the keyboard was last up - then in that case resign first responder for the search bar. Not sure if the keyboard will momentarily display though.
I have a very similar situation and may try that myself.
回答9:
Touching the clear button results in searchText being empty. Another way to achieve this is to check for empty text in - (void)searchBar:(UISearchBar *)bar textDidChange:(NSString *)searchText:
- (void)searchBar:(UISearchBar *)searchBar textDidChange:(NSString *)searchText
{
if([searchText length] == 0)
{
[self dismissSearch];
}
else
{
self.searchResultsTable.hidden = YES;
[self handleSearchForString:searchText];
}
}
- (void)dismissSearch
{
[self.searchBar performSelector: @selector(resignFirstResponder)
withObject: nil
afterDelay: 0.1];
self.searchResultsTable.hidden = YES;
}
回答10:
For those of you using the UISearchController in iOS 8 and up, you'll want to simply subclass the UISearchController. For completeness, you may also want to hide the cancel button, as I did, since clearing the text from the UISearchBar is effectively a cancel on the search. I've added that code below if you want to use it.
The benefit of this is that you'll be able to use this for any class and any view, rather than requiring a subclass of UIViewController. I'll even include how I initialize my UISearchController at the bottom of this solution.
FJSearchBar
This class only needs to be overridden if you want to hide the cancel button as I did. Marking searchController.searchBar.showsCancelButton = NO doesn't seem to work in iOS 8. I haven't tested iOS 9.
FJSearchBar.h
Empty, but placed here for completeness.
@import UIKit;
@interface FJSearchBar : UISearchBar
@end
FJSearchBar.m
#import "FJSearchBar.h"
@implementation FJSearchBar
- (void)setShowsCancelButton:(BOOL)showsCancelButton {
// do nothing
}
- (void)setShowsCancelButton:(BOOL)showsCancelButton animated:(BOOL)animated {
// do nothing
}
@end
FJSearchController
Here's where you want to make the real changes. I split the UISearchBarDelegate into its own category because, IMHO, the categories make the classes cleaner and easier to maintain. If you want to keep the delegate within the main class interface/implementation, you're more than welcome to do so.
FJSearchController.h
@import UIKit;
@interface FJSearchController : UISearchController
@end
@interface FJSearchController (UISearchBarDelegate) <UISearchBarDelegate>
@end
FJSearchController.m
#import "FJSearchController.h"
#import "FJSearchBar.h"
@implementation FJSearchController {
@private
FJSearchBar *_searchBar;
BOOL _clearedOutside;
}
- (UISearchBar *)searchBar {
if (_searchBar == nil) {
// if you're not hiding the cancel button, simply uncomment the line below and delete the FJSearchBar alloc/init
// _searchBar = [[UISearchBar alloc] init];
_searchBar = [[FJSearchBar alloc] init];
_searchBar.delegate = self;
}
return _searchBar;
}
@end
@implementation FJSearchController (UISearchBarDelegate)
- (BOOL)searchBarShouldBeginEditing:(UISearchBar *)searchBar {
// if we cleared from outside then we should not allow any new editing
BOOL shouldAllowEditing = !_clearedOutside;
_clearedOutside = NO;
return shouldAllowEditing;
}
- (void)searchBarSearchButtonClicked:(UISearchBar *)searchBar {
// hide the keyboard since the user will no longer add any more input
[searchBar resignFirstResponder];
}
- (void)searchBar:(UISearchBar *)searchBar textDidChange:(NSString *)searchText {
if (![searchBar isFirstResponder]) {
// the user cleared the search while not in typing mode, so we should deactivate searching
self.active = NO;
_clearedOutside = YES;
return;
}
// update the search results
[self.searchResultsUpdater updateSearchResultsForSearchController:self];
}
@end
Some parts to note:
- I've put the search bar and the
BOOLas private variables instead of properties because- They're more lightweight than private properties.
- They don't need to be seen or modified by the outside world.
- We check whether the
searchBaris the first responder. If it's not, then we actually deactivate the search controller because the text is empty and we're no longer searching. If you really want to be sure, you can also ensure thatsearchText.length == 0. searchBar:textDidChange:is invoked beforesearchBarShouldBeginEditing:, which is why we handled it in this order.- I update the search results every time the text changes, but you may want to move the
[self.searchResultsUpdater updateSearchResultsForSearchController:self];tosearchBarSearchButtonClicked:if you only want the search performed after the user presses the Search button.
回答11:
A Swift version of @boliva 's answer.
class MySearchContentController: UISearchBarDelegate {
private var searchBarShouldBeginEditing = true
func searchBar(_ searchBar: UISearchBar, textDidChange searchText: String) {
searchBarShouldBeginEditing = searchBar.isFirstResponder
}
func searchBarShouldBeginEditing(_ searchBar: UISearchBar) -> Bool {
defer {
searchBarShouldBeginEditing = true
}
return searchBarShouldBeginEditing
}
}
回答12:
I've run into this several times now. I really appreciate the answers that people have given.
Ultimately, I would really like to see Apple just allow us (the developers) to detect when the clear button has been pressed.
It is obvious that pressing it gets detected because any text in the search box gets cleared.
I am guessing that it just isn't very high up on their list of priorities right now... But I really wish someone at Apple would give UISearchBar a little love!
来源：https://stackoverflow.com/questions/1092246/uisearchbar-clearbutton-forces-the-keyboard-to-appear