IOS(UI)_Block傳值

ViewController.m

點擊事件：

- (IBAction)pushBtnAction:(id)sender
{

    BViewController *bViewController =[[BViewController alloc]initWithNibName:@"BViewController" bundle:[NSBundle mainBundle]];

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

    //哪個頁面需要值,哪個頁面實現方法
    bViewController.block = ^(NSString *string){

        self.label.text = string;
    };


}

先創建BViewController.h

定義了結構體：

#import <UIKit/UIKit.h>

//定義block
typedef void(^transferValue)(NSString *string);

@interface BViewController : UIViewController

@property (weak, nonatomic) IBOutlet UITextField *textField;

//把block作爲一個屬性,此處必須要用copy,因爲默認情況下,block是存檔在棧中，可能隨時被回收,需要copy操作
@property (nonatomic,copy)transferValue block;

@end

BViewController.m

- (IBAction)backBtnAction:(id)sender {

    self.block(self.textField.text);
    [self.navigationController popViewControllerAnimated:YES];

}