//  SecondViewController.h

#import <UIKit/UIKit.h>

typedef void(^blockName)(NSString *string);

@interface SecondViewController : UIViewController

@property (nonatomic, copy)blockName sendBlock;

@end

//  SecondViewController.m

- (IBAction)actionTow:(id)sender {

    self.sendBlock(self.textfile.text);

    [self dismissViewControllerAnimated:YES completion:nil];

}

//  ViewController.m

#import "ViewController.h"

#import "SecondViewController.h"

@interface ViewController ()

@property (weak, nonatomic) IBOutlet UILabel *lable;

@property (strong, nonatomic)SecondViewController *secondVC;

@end

@implementation ViewController

- (void)viewDidLoad {

    [super viewDidLoad];

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

    self.secondVC = [[SecondViewController alloc]init];

//    ARC情况下解决循环引用的方式： _weak

    __weak ViewController *weakThis = self;

    self.secondVC.sendBlock = ^(NSString *string){

//        如果要访问属性 还要使用__strong 来修饰。

        __strong ViewController *strongThis = weakThis;

        strongThis.lable.text = string;

    };

}

- (IBAction)actionOne:(id)sender {

    [self presentViewController:self.secondVC animated:YES completion:nil];

}