- (void)viewDidLoad {
[super viewDidLoad];
// static const char associatedButtonkey;
UIButton *btn = [UIButton buttonWithType:UIButtonTypeCustom];
[btn setTitle:@"点我" forState:UIControlStateNormal];
[self.view addSubview:btn];
[btn setFrame:CGRectMake(50, 50, 50, 50)];
btn.backgroundColor = [UIColor redColor];
[btn addTarget:self action:@selector(click:) forControlEvents:UIControlEventTouchUpInside];
// Do any additional setup after loading the view, typically from a nib.
}
-(void)click:(UIButton *)sender
{
NSString *message = @"你是谁";
UIAlertView *alert = [[UIAlertView alloc]initWithTitle:@"提示" message:@"我要传值·" delegate:self cancelButtonTitle:@"确定" otherButtonTitles:nil];
alert.delegate = self;
[alert show];
//#import <objc/runtime.h>头文件
//objc_setAssociatedObject需要四个参数：源对象，关键字，关联的对象和一个关联策略。
//1 源对象alert
//2 关键字 唯一静态变量key associatedkey
//3 关联的对象 sender
//4 关键策略 OBJC_ASSOCIATION_ASSIGN
// enum {
// OBJC_ASSOCIATION_ASSIGN = 0, 若引用/**< Specifies a weak reference to the associated object. */
// OBJC_ASSOCIATION_RETAIN_NONATOMIC = 1, /**< Specifies a strong reference to the associated object.
// * The association is not made atomically. */
// OBJC_ASSOCIATION_COPY_NONATOMIC = 3, /**< Specifies that the associated object is copied.
// * The association is not made atomically. */
// OBJC_ASSOCIATION_RETAIN = 01401, /**< Specifies a strong reference to the associated object.
// * The association is made atomically. */
// OBJC_ASSOCIATION_COPY = 01403 /**< Specifies that the associated object is copied.
// * The association is made atomically. */
// };
objc_setAssociatedObject(alert, @"msgstr", message,OBJC_ASSOCIATION_ASSIGN);
//把alert和message字符串关联起来，作为alertview的一部分，关键词就是msgstr，之后可以使用objc_getAssociatedObject从alertview中获取到所关联的对象，便可以访问message或者btn了
// 即实现了关联传值
objc_setAssociatedObject(alert, @"btn property",sender,OBJC_ASSOCIATION_ASSIGN);
}
-(void)alertView:(UIAlertView *)alertView clickedButtonAtIndex:(NSInteger)buttonIndex
{
//通过 objc_getAssociatedObject获取关联对象
NSString *messageString =objc_getAssociatedObject(alertView, @"msgstr");
UIButton *sender = objc_getAssociatedObject(alertView, @"btn property");
NSLog(@"%ld",buttonIndex);
NSLog(@"%@",messageString);
NSLog(@"%@",[[sender titleLabel] text]);
//使用函数objc_removeAssociatedObjects可以断开所有关联。通常情况下不建议使用这个函数，因为他会断开所有关联。只有在需要把对象恢复到“原始状态”的时候才会使用这个函数。
}
终端打印：
2015-07-22 16:18:35.294 test[5174:144121] 0
2015-07-22 16:18:35.295 test[5174:144121] 你是谁
2015-07-22 16:18:35.295 test[5174:144121] 点我
通过objc_setAssociatedObject也可以实现实例之间的数据传输 环境如下：两个viewcontroller，touchbegan点击屏幕，push到第二个viewcontroller在第二个c中获取到第一个c中的字符串，也可以是任何对象
ViewController.m
- (
void)viewDidLoad {
[
super viewDidLoad];
self.view.backgroundColor = [
UIColor redColor];
}
void)touchesBegan:(
NSSet *)touches withEvent:(
UIEvent *)event
- ( {
NSString *message =
@"这是一条需要传送的消息";
NSLog(
@"%p",message);
objc_setAssociatedObject(
self.navigationController,
@"test", message, OBJC_ASSOCIATION_ASSIGN);
Test2ViewController *test2 = [[Test2ViewController alloc] init];
[
self.navigationController pushViewController:test2 animated:
YES];
}
Test2ViewController.m
- (
void)viewDidLoad {
[
super viewDidLoad];
// Do any additional setup after loading the view.
NSString *messageString = objc_getAssociatedObject(
self.navigationController,
@"test");
self.view.backgroundColor = [
UIColor yellowColor];
NSLog(
@"%@",messageString);
NSLog(
@"%@",
self.navigationController.viewControllers);
NSLog(
@"%p",messageString);
}
终端打印如下：
连接 :https://my.oschina.net/wupengnash/blog/482377
连接:https://my.oschina.net/wupengnash/blog/482953