iOS-设计模式之Block

//  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];
}