#import <UIKit/UIKit.h>

NS_ASSUME_NONNULL_BEGIN

/**
 Provides extensions for `UIBarButtonItem`.
 */
@interface UIBarButtonItem (YYAdd)

/**
 The block that invoked when the item is selected. The objects captured by block
 will retained by the ButtonItem.
 
 @discussion This param is conflict with `target` and `action` property.
 Set this will set `target` and `action` property to some internal objects.
 */
@property (nullable, nonatomic, copy) void (^actionBlock)(id);

@end

#import "UIBarButtonItem+YYAdd.h"
#import "YYKitMacro.h"
#import <objc/runtime.h>

YYSYNTH_DUMMY_CLASS(UIBarButtonItem_YYAdd)


static const int block_key;

@interface _YYUIBarButtonItemBlockTarget : NSObject

@property (nonatomic, copy) void (^block)(id sender);

- (id)initWithBlock:(void (^)(id sender))block;
- (void)invoke:(id)sender;

@end

@implementation _YYUIBarButtonItemBlockTarget

- (id)initWithBlock:(void (^)(id sender))block{
    self = [super init];
    if (self) {
        _block = [block copy];
    }
    return self;
}

- (void)invoke:(id)sender {
    if (self.block) self.block(sender);
}

@end


@implementation UIBarButtonItem (YYAdd)

- (void)setActionBlock:(void (^)(id sender))block {
    _YYUIBarButtonItemBlockTarget *target = [[_YYUIBarButtonItemBlockTarget alloc] initWithBlock:block];
    objc_setAssociatedObject(self, &block_key, target, OBJC_ASSOCIATION_RETAIN_NONATOMIC);
    
    [self setTarget:target];
    [self setAction:@selector(invoke:)];
}

- (void (^)(id)) actionBlock {
    _YYUIBarButtonItemBlockTarget *target = objc_getAssociatedObject(self, &block_key);
    return target.block;
}

@end

利用_YYUIBarButtonItemBlockTarget 中间件给按钮添加block回调
setter方法中 给barbuttonitem 添加一个target与action，用runtime添加属性
getter方法中获取target的block