一、給類目加屬性時

#import <UIKit/UIKit.h>

@interface UITapGestureRecognizer (NSString)
@property(nonatomic,strong)NSString *dataStr;
@end

#import "UITapGestureRecognizer+NSString.h"
#import <objc/runtime.h>
static char * personNameKey = "personNameKey";

@implementation UITapGestureRecognizer
 
 (NSString)

- (void)setDataStr:(NSString *)dataStr{
//    objc_setAssociatedObject(self, personNameKey, dataStr, OBJC_ASSOCIATION_COPY_NONATOMIC);
    objc_setAssociatedObject(self, @selector(dataStr), dataStr, OBJC_ASSOCIATION_COPY_NONATOMIC);
}

- (NSString*)dataStr {
    return objc_getAssociatedObject(self
 
, _cmd);
//    return objc_getAssociatedObject(self, personNameKey);
}
@end

二、交換方法時

@implementation UITableView (CNEmpty)
+ (void)load{
    [self changeSEL];
}

+ (void)changeSEL{
    Method formMethod = class_getInstanceMethod(self, @selector(reloadData));
    Method toMethod = class_getInstanceMethod(self
 
, @selector(cn_reloadData));
//    if (class_addMethod(self, @selector(reloadData), method_getImplementation(toMethod), method_getTypeEncoding(toMethod))){
        method_exchangeImplementations(formMethod, toMethod);
//    }
}

- (void)cn_reloadData{
    [self cn_reloadData];
    [self addOrMoveEmptyView];

}

-(void)setHalvingLine:(UITableViewCell *)cell{
    if ([cell respondsToSelector:@selector(setSeparatorInset:)]) {
        [cell setSeparatorInset:UIEdgeInsetsZero];
    }

    if ([cell respondsToSelector:@selector(setLayoutMargins:)]) {
        [cell setLayoutMargins:UIEdgeInsetsZero];
    }
}
@end