obj-c 保護你的delegate method calling

@protocol SearchViewDelegate<NSObject>

@optional

- (void)searchTextFieldDidBeginEditing;

- (void)onSearchTextFieldValueChanged:(NSString *)text;

@end

@interface SearchView()

@end

@implementation SearchView

typedef struct {

    unsigned int searchTextFieldDidBeginEditing:1;

    unsigned int onSearchTextFieldValueChanged:1;

} DelegateRespondsTo;

DelegateRespondsTo delegateRespondsTo;

- (void)setDelegate:(id <SearchViewDelegate>)aDelegate {

    if (_delegate != aDelegate) {

        _delegate = aDelegate;

        

        delegateRespondsTo.searchTextFieldDidBeginEditing = [_delegate respondsToSelector:@selector(searchTextFieldDidBeginEditing)];

        delegateRespondsTo.onSearchTextFieldValueChanged = [_delegate respondsToSelector:@selector(onSearchTextFieldValueChanged:)];

    }

}