这次要讲的是如何从A进入B,在B输入值后回传给A,那么在IOS中实现这个功能就需要使用到Delegate(委托协议)。
其中有两个ViewController分别对应两个界面,一个协议PassValueDelegate用来实现传值协议,UserEntity是传递数据的对象。
协议中声明的方法:
#import <Foundation/Foundation.h> @class UserEntity; @protocol PassValueDelegate <NSObject> -(void)passValue:(UserEntity *)value; @end
在第一个窗口实现协议:
//第一个窗口遵守PassValueDelegate @interface ViewController : UIViewController<PassValueDelegate> @property (retain, nonatomic) IBOutlet UILabel *nameLabel; @property (retain, nonatomic) IBOutlet UILabel *ageLabel; @property (retain, nonatomic) IBOutlet UILabel *gendarLabel; - (IBAction)openBtnClicked:(id)sender; @end
.m文件中实现协议的方法
//实现协议,在第一个窗口显示在第二个窗口输入的值 -(void)passValue:(UserEntity *)value { self.nameLabel.text = value.userName; self.ageLabel.text = [NSString stringWithFormat:@"%d",value.age]; self.gendarLabel.text = value.gendar; }
点击按钮所触发的事件:
//点击进入第二个窗口的方法 - (IBAction)openBtnClicked:(id)sender { SecondViewController *secondView = [[SecondViewController alloc] initWithNibName:@"SecondViewController" bundle:[NSBundle mainBundle]]; //设置第二个窗口中的delegate为第一个窗口的self secondView.delegate = self; [self.navigationController pushViewController:secondView animated:YES]; [secondView release]; }
第二个窗口中声明一个NSObject对象,该对象遵守PassValueDelegate协议:
@interface SecondViewController : UIViewController @property (retain, nonatomic) IBOutlet UITextField *nameTextField; @property (retain, nonatomic) IBOutlet UITextField *ageTextFiled; @property (retain, nonatomic) IBOutlet UITextField *gendarTextField; //这里用assign而不用retain是为了防止引起循环引用。 @property(nonatomic,assign) NSObject<PassValueDelegate> *delegate; - (IBAction)okBtnClicked:(id)sender; - (IBAction)closeKeyboard:(id)sender; @end
输入完毕后,点击按钮所触发的事件:
- (IBAction)okBtnClicked:(id)sender { UserEntity *userEntity = [[UserEntity alloc] init]; userEntity.userName = self.nameTextField.text; userEntity.gendar = self.gendarTextField.text; userEntity.age = [self.ageTextFiled.text intValue]; //通过委托协议传值 [self.delegate passValue:userEntity]; //退回到第一个窗口 [self.navigationController popViewControllerAnimated:YES]; [userEntity release]; }