点击'X'元素时触发UISearchBar和事件

On the UISearchBar, there's an X element that allows you to clear all of the contents at once. Is there a way to get notified when this happens?

在UISearchBar上,有一个X元素允许您一次清除所有内容。有没有办法在发生这种情况时收到通知?

UISearchBarDelegate::searchBarCancelButtonClicked is fired only when the "Cancel" button is tapped.

只有在点击“取消”按钮时才会触发UISearchBarDelegate :: searchBarCancelButtonClicked。

4 个解决方案

#1

The UISearchBar doesn't have a delegate method for this event. You can nearly get what you want by implementing the textDidChange: method of the callback delegate and checking for an empty string.

UISearchBar没有此事件的委托方法。通过实现回调委托的textDidChange:方法并检查空字符串,您几乎可以获得所需的内容。

I don't recommend it, but there is another possible way. The UISearchBar is composed of a UITextField, which does have a delegate method that is called when the user taps the clear button (textFieldShouldClear:). You can get the UITextField by traversing the UISearchBar's child views:

我不推荐它,但还有另一种可能的方法。 UISearchBar由一个UITextField组成,它有一个委托方法,当用户点击clear按钮(textFieldShouldClear :)时会调用该方法。您可以通过遍历UISearchBar的子视图来获取UITextField:

(this is in the context of a derived UISearchBar class)

(这是在派生的UISearchBar类的上下文中)

- (UIView*) textField
{
    for (UIView* v in self.subviews)
    {
        if ( [v isKindOfClass: [UITextField class]] )
            return v;
    }

    return nil;
}

from here, you could re-assign the UITextField delegate to your own implementation, taking care to forward delegate calls to the old delegate. This way you could intercept textFieldShouldClear:. Or if it turns out the UISearchBar is the delegate for the UITextField it contains you could swizzle the call to textFieldShouldClear:... Not ideal, clearly, but technically feasible.

从这里,您可以将UITextField委托重新分配给您自己的实现,注意将委托调用转发给旧委托。这样你就可以拦截textFieldShouldClear:。或者如果事实证明UISearchBar是它包含的UITextField的委托,你可以调用textFieldShouldClear:...不理想,但技术上可行。

#2

I had the same issue and I solved this issue by using this function.

我有同样的问题,我通过使用此功能解决了这个问题。

- (void)searchBar:(UISearchBar *)searchBar textDidChange:(NSString *)searchText 
{
    // This method has been called when u enter some text on search or Cancel the search.
    if([searchText isEqualToString:@""] || searchText==nil) {
        // Nothing to search, empty result.

       [UIView animateWithDuration:0.2 animations:^ {
        //Reposition search bar 
        [_searchBar setFrame:CGRectMake(230, 26, 43, 44)];
        [_searchBar setNeedsLayout];
       }];
    }
}

#3

Here is an answer from a previous question, this should do exactly what you want. UISearchbar clearButton forces the keyboard to appear

以下是上一个问题的答案,这应该完全符合您的要求。 UISearchbar clearButton强制键盘出现

#4

Here is "Method Swizzling" solution.

这是“Method Swizzling”解决方案。

Create a new Category of UISearchBar. This category create a new method and swizzle method between -(BOOL)textFieldShouldClear:(UITextField *)textField; and -(BOOL)jbm_textFieldShouldClear:(UITextField *)textField in runtime.

创建一个新的UISearchBar类别。这个类创建了一个新方法和swizzle方法 - (BOOL)textFieldShouldClear:(UITextField *)textField;和 - (BOOL)jbm_textFieldShouldClear :( UITextField *)运行时的textField。

Customize a new Protocol of UISearchBarDelegate in order to add a new method - (void)searchBarClearButtonClicked:(id)sender;

自定义UISearchBarDelegate的新协议以添加新方法 - (void)searchBarClearButtonClicked:(id)sender;

UISearchBar+JMBTextFieldControl.h

    @protocol UISearchBarWithClearButtonDelegate <UISearchBarDelegate>
    @optional
    - (void)searchBarClearButtonClicked:(id)sender;
    @end

    @interface UISearchBar (JMBTextFieldControl)
    @end

UISearchBar+JMBTextFieldControl.m

    #import "UISearchBar+JMBTextFieldControl.h"
    #import <objc/runtime.h>

    @implementation NSObject (Swizzling)

    + (void)brc_swizzleMethod:(SEL)origSelector withMethod:(SEL)newSelector
    {
        Method origMethod = class_getInstanceMethod(self, origSelector);
        Method newMethod = class_getInstanceMethod(self, newSelector);

        if(class_addMethod(self, origSelector, method_getImplementation(newMethod), method_getTypeEncoding(newMethod)))
            class_replaceMethod(self, newSelector, method_getImplementation(origMethod), method_getTypeEncoding(origMethod));
        else
            method_exchangeImplementations(origMethod, newMethod);
    }
    @end

    @implementation UISearchBar (JMBTextFieldControl)

    + (void)load {
        [self brc_swizzleMethod:@selector(textFieldShouldClear:) withMethod:@selector(jbm_textFieldShouldClear:)];
    }

    - (id<UISearchBarWithClearButtonDelegate>)jbm_customDelegate {
        if( [[self delegate] conformsToProtocol:@protocol(UISearchBarWithClearButtonDelegate)] )
            return (id<UISearchBarWithClearButtonDelegate>)[self delegate];
        else
            return nil;
    }

    - (BOOL)jbm_textFieldShouldClear:(UITextField *)textField
    {
        if ( [[self jbm_customDelegate] respondsToSelector:@selector(searchBarClearButtonClicked:)] )
            [[self jbm_customDelegate] searchBarClearButtonClicked:self];

        return [self jbm_textFieldShouldClear:textField];
    }

    @end

Reference

Dave DeLong - How to add a method to an existing protocol in Cocoa?

Dave DeLong - 如何在Cocoa中为现有协议添加方法?
Nikolay Vlasov - CCBottomRefreshControl

Nikolay Vlasov - CCBottomRefreshControl

#1