iOS---block反向传值

//从1界面跳转到2,返回第2个界面的数据

/** ---------------------------------------------------------------------------*/

//第1个界面的.m

Select *select= [[Select alloc]init];

select.hidesBottomBarWhenPushed=YES;

[self.navigationController
pushViewController:select animated:YES];

select.block = ^(NSString *str){

_value1 = str;

};

/** ---------------------------------------------------------------------------*/
//第2个界面的.h

@interface Select :
UIViewController

typedef void (^ablock)(NSString *str);

@property (nonatomic,
copy) ablock block;

@end

/** ---------------------------------------------------------------------------*/

//第2个界面的.m

//跳转上一界面

if (self.block) {

self.block(要传得值);

//
必须写在pop之前

[self.navigationController
popToViewController:[self.navigationController.viewControllers
objectAtIndex:2]
animated:YES];

}