iOS - 监听UITextField键盘删除键之分类

#import 

@protocol RCSBackWordTextFieldDelegate <NSObject>

- (void)textFieldDidDeleteBackward:(UITextField *)textField;

@end

@interface UITextField (RCSBackWord)

@property (weak, nonatomic) id<RCSBackWordTextFieldDelegate> delegate;

@end

#import "UITextField+RCSBackWord.h"

#import 

@implementation UITextField (RCSBackWord)

+ (void)load

{

    //! 交换2个方法中的IMP

    Method method1 = class_getInstanceMethod([self class], NSSelectorFromString(@"deleteBackward"));

    Method method2 = class_getInstanceMethod([self class], @selector(Rcs_deleteBackward));

    method_exchangeImplementations(method1, method2);

    //! 下面这个交换主要解决大于等于8.0小于8.3系统不调用deleteBackward的问题

    Method method3 = class_getInstanceMethod([self class], NSSelectorFromString(@"keyboardInputShouldDelete:"));

    Method method4 = class_getInstanceMethod([self class], @selector(Rcs_keyboardInputShouldDelete:));

    method_exchangeImplementations(method3, method4);

}

- (void)Rcs_deleteBackward

{

    [self Rcs_deleteBackward];

    if ([self.delegate respondsToSelector:@selector(textFieldDidDeleteBackward:)]){

        id <RCSBackWordTextFieldDelegate> delegate = (id<RCSBackWordTextFieldDelegate>)self.delegate;

        [delegate textFieldDidDeleteBackward:self];

    }

}

- (BOOL)Rcs_keyboardInputShouldDelete:(UITextField *)textField {

    

    BOOL shouldDelete = [self Rcs_keyboardInputShouldDelete:textField];

    

    BOOL isMoreThanIos8_0 = ([[[UIDevice currentDevice] systemVersion] floatValue] >= 8.0f);

    

    BOOL isLessThanIos8_3 = ([[[UIDevice currentDevice] systemVersion] floatValue] < 8.3f);

    

    if (![textField.text length] && isMoreThanIos8_0 && isLessThanIos8_3) {

        

        [self deleteBackward];

    }

    

    return shouldDelete;

}

@end