1. runtime俗称（运行时）
2.理解（优点）：可以不破坏他人项目中已有的类的封装,与已有类完全分开,保持了模块化的独立性,添加自己想要添加的属性
3.实现：UIBarButtonItem已blok的形式实现
#import@interface UIBarButtonItem (BlockSupport)
//UIBarButtonItem 的标题
- (nullable instancetype)initWithTitle:(nullable NSString *)title style:(UIBarButtonItemStyle)style andBlock:(void(^)())clickBlock;
//UIBarButtonItem 的图片，
-(nullable instancetype)initWithImage:(nullable UIImage*)image style:(UIBarButtonItemStyle)style andBlock:(void(^)())clickBlock;
@end
#import "UIBarButtonItem+BlockSupport.h"
// 导入runtime
#import <objc/runtime.h>
const char *barbuttonItemBlockKey = "barbuttonItemBlockKey";
@implementation UIBarButtonItem (BlockSupport)
- (instancetype)initWithTitle:(nullable NSString *)title style:(UIBarButtonItemStyle)style andBlock:(void(^)())clickBlock
{
self = [self initWithTitle:title style:style target:self action:@selector(handleClick)];
if (self) {
objc_setAssociatedObject(self, barbuttonItemBlockKey, clickBlock, OBJC_ASSOCIATION_COPY);
}
return self;
}
- (void)handleClick
{
void (^block)() = objc_getAssociatedObject(self, barbuttonItemBlockKey);
if (block ) {
block();
}
}
-(nullable instancetype)initWithImage:(nullable UIImage*)image style:(UIBarButtonItemStyle)style andBlock:(void(^)())clickBlock
{
self = [self initWithImage:image style:style target:self action:@selector(handleClickImage)];
if (self) {
objc_setAssociatedObject(self, barbuttonItemBlockKey, clickBlock, OBJC_ASSOCIATION_COPY);
}
return self;
}
- (void)handleClickImage
{
void (^block)() = objc_getAssociatedObject(self, barbuttonItemBlockKey);
if (block ) {
block();
}
}
@end
