objective-c - 将数据传递给 parentViewController [iOS]

Question

我有这个 Storyboard:

当我在第一个 View Controller (称为 newCourseViewController)中按下“Insegnante”按钮时，它会显示一个带有教师列表的表格 View 。当我按下老师(并调用方法 tableView:canEditRowAtIndexPath:)时，我希望 UITableViewController 将按下的对象“传递”到第一个 View Controller 。

这是我的第一个 View Controller newCourseViewController.h

#import <UIKit/UIKit.h>
#import "Teacher.h"

@interface newCourseViewController : UIViewController

@property (nonatomic , strong) Teacher *teacher;

@end

这是我第一个 View Controller 的代码newCourseViewController.m(只有重要的代码)

#import "newCourseViewController.h"
#import "Courses.h"
#import "Teacher.h"
#import "addTeacherToCourseViewController.h"

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

@implementation newCourseViewController


- (void)viewDidLoad
{
    [super viewDidLoad];
    // Do any additional setup after loading the view.
}

- (void)didReceiveMemoryWarning
{
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}

-(void)setTeacher:(Teacher *)teacher
{
    self.teacher = teacher;
    NSLog(@"Maestro settato!");
}

-(void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender
{
    if ([segue.identifier isEqualToString:@"addTeacherToCourse"]) {
        [segue.destinationViewController setPreviousViewController:self];
    }
}

现在是第二个 View Controller 的代码 addTeacherToCourseViewController-h

@interface addTeacherToCourseViewController : UITableViewController

@property (nonatomic , weak) id previousViewController;

@end

和addTeacherToCourseViewController.m(只有重要的方法)

-(void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{
    Teacher *teacher = [self.teachers getTeacherInPosition:indexPath.row];
    [self.previousViewController setTeacher:teacher];
    [self.navigationController popViewControllerAnimated:YES];

}

在 prepareForSegue 方法的第一个 View Controller 中，我将自己设置为第二个 View 中的 previousViewController。然后我“通过”老师选择的，然后我解散第二个 View Controller 。当应用程序执行 [self.navigationController popViewControllerAnimated:YES]; Xcode 崩溃和模拟器崩溃。我不知道是什么问题。你能帮帮我吗？

Answer 1

要将值发送到父 Controller ，您必须使用协议(protocol)。我将提供您应该采取的正确步骤，以使您想要的功能正常工作。

1.为您的 AddTeacherToCourseController 创建协议(protocol)。在您的 AddTeacherToCourseController.h 中，在导入的正下方添加以下内容:

@protocol AddTeacherToCourseControllerProtocol <NSObject>
    - (void)yourDelegateMethod:(Teacher *)insegnante;
@end

在接口(interface)标签下面添加:

@property (strong, nonatomic) id <AddTeacherToCourseControllerProtocol> delegate;

2。在 AddTeacherToCourseController.m 中:

-(void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{
    // I would use the existing array you are using to display the teachers in order to select the correct one you want to send back like this:
    // Teacher *teacher = [self.teachers getTeacherInPosition:indexPath.row];
    [self.delegate yourDelegateMethod:[yourTeacherArray objectAtIndex:indexPath.row]];
}

[此方法将通过协议(protocol)调用您的委托(delegate)方法并将您选择的教授传递给父 Controller ]

3。在你的父 Controller 中，你的 newCourseViewController.h 在接口(interface)行之后添加:

<AddTeacherToCourseControllerProtocol>

4.如果您没有 Insegnante 按钮操作，请在界面构建器中创建一个 [拖动和命名]。然后将以下内容添加到此操作中:

// assuming your storyboard is named MainStoryboard. here you create your segue programmatically:
UIStoryboard *storyBoard = [UIStoryboard storyboardWithName:@"MainStoryboard" bundle:nil];
addTeacherToCourseViewController *addTeacherController = (addTeacherToCourseViewController *)[storyBoard instantiateViewControllerWithIdentifier:@"addTeacherToCourseViewController"];
addTeacherController.delegate = self;
[self.navigationController pushViewController:addTeacherController animated:YES];

5.在界面生成器中:

• 从 Insegnante 按钮中删除您的 segue。
• 将“addTeacherToCourseViewController”的 Storyboard Id 修改为“addTeacherToCourseViewController”

6.在 newCourseViewController.h 中编写您的委托(delegate)方法:

- (void)yourDelegateMethod:(Teacher *)insegnante{
    // Do whatever you want with your Insegnante
    // and be sure to pop the second controller from the view stack:
    [self.navigationController popViewControllerAnimated:YES];
}

如果您有任何问题，请告诉我，如果我的回答对任何人有帮助。