.h 檔案

#import <UIKit/UIKit.h>

@protocol TTTextFieldDelegate <UITextFieldDelegate>

@optional
- (void)textFieldDidDeleteBackward:(UITextField *)textField;
@end

@interface UITextField (GTExtend)

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

@end

/**
 *  監聽刪除按鈕
 *  object:UITextField
 */
 

extern NSString * const TTTextFieldDidDeleteBackwardNotification;

.m 檔案

#import "UITextField+GTExtend.h"
#import <objc/runtime.h>

NSString * const TTTextFieldDidDeleteBackwardNotification = @"textfield_did_notification";

@implementation UITextField (GTExtend)

+ (void)load {
    Method method1 = class_getInstanceMethod([self
 
 class], NSSelectorFromString(@"deleteBackward"));
    Method method2 = class_getInstanceMethod([self class], @selector(tt_deleteBackward));
    method_exchangeImplementations(method1, method2);
    //! 下面這個交換主要解決大於等於8.0小於8.3系統不呼叫deleteBackward的問題

    Method method3 = class_getInstanceMethod([self class], NSSelectorFromString(@"keyboardInputShouldDelete:"
 
));
    Method method4 = class_getInstanceMethod([self class], @selector(tt_keyboardInputShouldDelete:));
    method_exchangeImplementations(method3, method4);
}

- (void)tt_deleteBackward {
    [self tt_deleteBackward];

    if ([self.delegate respondsToSelector:@selector(textFieldDidDeleteBackward:)])
    {
        id <TTTextFieldDelegate> delegate  = (id<TTTextFieldDelegate>)self.delegate;
        [delegate textFieldDidDeleteBackward:self];
    }

    [[NSNotificationCenter defaultCenter] postNotificationName:TTTextFieldDidDeleteBackwardNotification object:self];
}

- (BOOL)tt_keyboardInputShouldDelete:(UITextField *)textField {
    BOOL shouldDelete = [self tt_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;

}