runtime 学习关联对象（附带一个：全屏侧滑返回扩展）

前言：这是我偶然间看见的一种利用runtime原理写向右侧滑返回上一页的类扩展，
用起来很方便，直接将扩展拉进项目里面即可，然后所有的push的控制器都可以右滑返回上一页了

首先需要了解一下 runtme的关联方法objc_setAssociatedObject

关联对象不是为类\对象添加属性或者成员变量(因为在设置关联后也无法通过ivarList或者propertyList取得) ，而是为类添加一个相关的对象，通常用于存储类信息，例如存储类的属性列表数组，为将来字典转模型的方便。

objc_setAssociatedObject方法的参数解释:

1. 第一个参数id object, 当前对象

2. 第二个参数const void *key, 关联的key，是c字符串

3. 第三个参数id value, 被关联的对象的值

4. 第四个参数objc_AssociationPolicy policy关联引用的规则

使用方式一：给分类添加属性

@implementation ViewController

- (void)viewDidLoad {

[super viewDidLoad];

// Do any additional setup after loading the view, typically from a nib.

// 给系统NSObject类动态添加属性name

NSObject *objc = [[NSObject alloc] init];

objc.name = @"哈哈";

NSLog(@"%@",objc.name);

}

@end

// 定义关联的key

static const char *key = "name";

@implementation NSObject (Property)

- (NSString *)name

{

// 根据关联的key，获取关联的值。

return objc_getAssociatedObject(self, key);

}

- (void)setName:(NSString *)name

{

// 第一个参数：给哪个对象添加关联

// 第二个参数：关联的key，通过这个key获取

// 第三个参数：关联的value

// 第四个参数:关联的策略

objc_setAssociatedObject(self, key, name, OBJC_ASSOCIATION_RETAIN_NONATOMIC);

}

@end```



使用方式二：给对象添加关联对象。

/**

• 删除点击

• @param recId 购物车ID

*/

• (void)shopCartCell:(BSShopCartCell *)shopCartCell didDeleteClickedAtRecId:(NSString *)recId

{

UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"" message:@"确认要删除这个宝贝" delegate:self cancelButtonTitle:@"取消" otherButtonTitles:@"确定", nil];

// 传递多参数

objc_setAssociatedObject(alert, "suppliers_id", @"1", OBJC_ASSOCIATION_RETAIN_NONATOMIC);

objc_setAssociatedObject(alert, "warehouse_id", @"2", OBJC_ASSOCIATION_RETAIN_NONATOMIC);

alert.tag = [recId intValue];

[alert show];

}

/**

• 确定删除操作

*/

• (void)alertView:(UIAlertView *)alertView clickedButtonAtIndex:(NSInteger)buttonIndex {

if (buttonIndex == 1) {

NSString *warehouse_id = objc_getAssociatedObject(alertView, "warehouse_id");

NSString *suppliers_id = objc_getAssociatedObject(alertView, "suppliers_id");

NSString *recId = [NSString stringWithFormat:@"%ld",(long)alertView.tag];

}

}

下面是右滑返回 ，我做了详细注释，

import@interface UINavigationController (XWFullScreenLeftSlidPop)

@property(strong, nonatomic) UIPanGestureRecognizer * xw_popgestureRecoginizer;

@end```

////  UINavigationController+XWFullScreenLeftSlidPop.m//  KouDaiGuangBo////  Created by 文 on 2016/12/26.//  Copyright © 2016年 CSC. All rights reserved.//#import "UINavigationController+XWFullScreenLeftSlidPop.h"#import@interface XWFullScreenPopGestureRecognizerDelegate :NSObject@property(weak, nonatomic) UINavigationController * navigationController;

@end

@implementation XWFullScreenPopGestureRecognizerDelegate

-(BOOL)gestureRecognizerShouldBegin:(UIPanGestureRecognizer *)gestureRecognizer

{

NSLog(@"----%ld",self.navigationController.viewControllers.count);

// 判断是否是更新

//    if (self.navigationController.viewControllers.count<=1) {

//

//        return NO;

//    }

//  如果正在转场动画

if ([[self.navigationController valueForKey:@"_isTransitioning"] boolValue]) {

return NO;

}

//判断手指移动方向

CGPoint translation = [gestureRecognizer translationInView:gestureRecognizer.view];

if (translation.x<=0) {

// 左滑

return NO;

}

return YES;

}

@end

@implementation UINavigationController (XWFullScreenLeftSlidPop)

+(void)load

{

// 交叉方法替换系统的 pushViewController

Method methodNomer = class_getInstanceMethod([self class], @selector(pushViewController:animated:));

Method othermethod = class_getInstanceMethod([self class],@selector(XW_pushViewController:animated:));

method_exchangeImplementations(methodNomer, othermethod);

}

-(void)XW_pushViewController:(UIViewController *)ViewController animated:(BOOL)animated

{

// 替换的目的是为了 添加一个自己的手势

//拿到navigationController原有的pop手势：self.interactivePopGestureRecognizer

// self.interactivePopGestureRecognizer是navigationController自带的pop手势

if(![self.interactivePopGestureRecognizer.view.gestureRecognizers containsObject:self.xw_popgestureRecoginizer])// 判断是否是自己的手势

{

// 添加自己的手势

[self.interactivePopGestureRecognizer.view addGestureRecognizer:self.xw_popgestureRecoginizer];

NSArray * tagets =[self.interactivePopGestureRecognizer valueForKey:@"targets"];

id internalTarget = [tagets.firstObject valueForKey:@"target"];

SEL internalAction = NSSelectorFromString(@"handleNavigationTransition:");

// 拦截系统的所有的handleNavigationTransition：换成自己自己添加的手势来识别

self.xw_popgestureRecoginizer.delegate = [self xw_fullscreenPopGestuieRecoginzerDelegate];

// 自己的手势调用系统的手势方法 handleNavigationTransition

[self.xw_popgestureRecoginizer addTarget:internalTarget action:internalAction];

// 禁止系统的手势交互

self.interactivePopGestureRecognizer.enabled = NO;

}

if (![self.viewControllers containsObject:ViewController]) {

// 交叉方法调用系统的pushViewController:方法

// 调用XW_pushViewController = 调用pushViewController 因为这两个方法互换了

[self XW_pushViewController:ViewController animated:animated];

}

}

-(XWFullScreenPopGestureRecognizerDelegate*)xw_fullscreenPopGestuieRecoginzerDelegate

{

// 给navigationController 添加一个xw_fullscreenPopGestuieRecoginzerDelegate 属性

// 获取关联对象

XWFullScreenPopGestureRecognizerDelegate *delegate = objc_getAssociatedObject(self, _cmd);

//如果未关联重新关联

if (!delegate) {

delegate = [[XWFullScreenPopGestureRecognizerDelegate alloc] init];

objc_setAssociatedObject(self, _cmd, delegate, OBJC_ASSOCIATION_RETAIN_NONATOMIC);

}

//返回关联对象

return delegate;

}

-(UIPanGestureRecognizer *)xw_popgestureRecoginizer

{

// 给navigationController 添加一个xw_popgestureRecoginizer属性

// 获取关联对象

UIPanGestureRecognizer *panGestureRecoginizer =objc_getAssociatedObject(self, _cmd);

//如果未关联重新关联

if (!panGestureRecoginizer) {

panGestureRecoginizer =[[UIPanGestureRecognizer alloc] init];

panGestureRecoginizer.maximumNumberOfTouches = 1;

//将self与panGestureRecoginizer关联起来

objc_setAssociatedObject(self, _cmd, panGestureRecoginizer, OBJC_ASSOCIATION_RETAIN_NONATOMIC);

}

//返回关联对象

return panGestureRecoginizer;

}

@end```