Question

我在项目中创建了两个视图。我想能够点击主视图上的按钮，然后会弹出另一个视图（ChooseCar），允许用户选择一些东西，然后它将使用输入的信息重新打开旧视图（ViewController）。我已经为它完成了代码，但由于某种原因，当我点击按钮时，屏幕变黑，没有任何事情发生，我很确定这是非常简单的事情，我无法理解我的头脑在它周围。

我将附上以下观点的代码，谢谢。

的 ViewController.h

//
//  ViewController.h
//
//  Created by Curtis Boylan on 24/11/2016.
//  Copyright © 2016. All rights reserved.
//

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

@interface ViewController : UIViewController <ChooseCarDelegate>
- (IBAction)chooselocation;
@property (strong, nonatomic) IBOutlet UILabel *wherelocation;

@end

ViewController.m

//
//  ViewController.m
//
//  Created by Curtis Boylan on 24/11/2016.
//  Copyright © 2016. All rights reserved.
//

#import "ViewController.h"

@interface ViewController ()
@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad]; 
}
- (void)didReceiveMemoryWarning {
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}
-(UIStatusBarStyle)preferredStatusBarStyle{
    return UIStatusBarStyleLightContent;
}
- (IBAction)chooselocation {
    ChooseCar *acController = [[ChooseCar alloc] init];
   // acController.delegate = self;
    [self presentViewController:acController animated:YES completion:nil];}

- (void)addItemViewController:(ChooseCar *)controller didFinishEnteringItem:(NSString *)item
{
    NSLog(@"This was returned from ChooseCar %@",item);
}

@end

ChooseCar.h

//
//  ChooseCar.h
//
//  Created by Curtis Boylan on 24/11/2016.
//  Copyright © 2016. All rights reserved.
//

#import <UIKit/UIKit.h>
@class ChooseCar;

@protocol ChooseCarDelegate <NSObject>
- (void)addItemViewController:(ChooseCar *)controller didFinishEnteringItem:(NSString *)item;
@end

@interface ChooseCar : UIViewController

@end

ChooseCar.m

//
//  ChooseCar.m
//
//  Created by Curtis Boylan on 24/11/2016.
//  Copyright © 2016. All rights reserved.
//

#import "ChooseCar.h"

@interface ChooseCar ()
@property (nonatomic, weak) id <ChooseCarDelegate> delegate;
@end

@implementation ChooseCar

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

    NSString *itemToPassBack = @"Pass this value back to ViewControllerA";
    [self.delegate addItemViewController:self didFinishEnteringItem:itemToPassBack];

}

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

/*
#pragma mark - Navigation

// In a storyboard-based application, you will often want to do a little preparation before navigation
- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender {
    // Get the new view controller using [segue destinationViewController].
    // Pass the selected object to the new view controller.
}
*/

@end

Answer 1

很容易做到：

1）我相信您的ChooseCar vc是在storyboard中创建的。如果是，您应该像这样设置Storyboard ID：

2）在ViewController.m中，将chooselocation方法更新为：

- (IBAction)chooselocation {
//ChooseCar *acController = [[ChooseCar alloc] init];

UIStoryboard *sb = [UIStoryboard storyboardWithName:@"Main" bundle:nil];


ChooseCar *acController = [sb instantiateViewControllerWithIdentifier:@"ChooseCar"];

[self presentViewController:acController animated:YES completion:nil];

}

修改

如果您想通过委托传递值：

在我的基础上。

1）将此代码@property (nonatomic, weak) id <ChooseCarDelegate> delegate;从您的ChooseCar.m剪切为ChooseCar.h，确保ChooseCar.h像这样：

#import <UIKit/UIKit.h> @class ChooseCar; @protocol ChooseCarDelegate <NSObject> - (void)addItemViewController:(ChooseCar *)controller didFinishEnteringItem:(NSString *)item; @end @interface ChooseCar : UIViewController @property (nonatomic, weak) id <ChooseCarDelegate> delegate; @end

2）在ViewController.m中，您应该遵守protocal，并设置caController代表。

#import "ChooseCar.h" #import "ViewController.h" @interface ViewController () <ChooseCarDelegate> @end @implementation ViewController - (void)viewDidLoad { [super viewDidLoad]; } - (void)didReceiveMemoryWarning { [super didReceiveMemoryWarning]; // Dispose of any resources that can be recreated. } -(UIStatusBarStyle)preferredStatusBarStyle{ return UIStatusBarStyleLightContent; } - (IBAction)chooselocation { //ChooseCar *acController = [[ChooseCar alloc] init]; UIStoryboard *sb = [UIStoryboard storyboardWithName:@"Main" bundle:nil]; ChooseCar *acController = [sb instantiateViewControllerWithIdentifier:@"ChooseCar"]; acController.delegate = self; [self presentViewController:acController animated:YES completion:nil]; } - (void)addItemViewController:(ChooseCar *)controller didFinishEnteringItem:(NSString *)item { NSLog(@"This was returned from ChooseCar %@",item); } @end

3）如果您想传递该值，您应该将此代码用于您的操作：

NSString *itemToPassBack = @"Pass this value back to ViewControllerA"; [self.delegate addItemViewController:self didFinishEnteringItem:itemToPassBack];

Answer 2

使用以下内容替换您的代码：

<强> ViewController.h

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

@interface ViewController : UIViewController <ChooseCarDelegate>
- (IBAction)chooselocation;
@property (strong, nonatomic) IBOutlet UILabel *wherelocation;

@end

<强> ViewController.m

#import "ViewController.h"

@interface ViewController ()
{
    ChooseCar *acController;
}
@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
}
- (void)didReceiveMemoryWarning {
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}
-(UIStatusBarStyle)preferredStatusBarStyle{
    return UIStatusBarStyleLightContent;
}
- (IBAction)chooselocation {

    acController = [self.storyboard instantiateViewControllerWithIdentifier:@"ChooseCar"];
    acController.delegate = self;
    [self presentViewController:acController animated:YES completion:nil];

}

- (void)addItemViewController:(ChooseCar *)controller didFinishEnteringItem:(NSString *)item
{
    [acController dismissViewControllerAnimated:true completion:nil];
    NSLog(@"This was returned from ChooseCar %@",item);
}

@end

还在故事板中设置故事板ID。有关详细信息，请参阅随附的屏幕截图：

<强> ChooseCar.h

#import <UIKit/UIKit.h>
@class ChooseCar;

@protocol ChooseCarDelegate <NSObject>
- (void)addItemViewController:(ChooseCar *)controller didFinishEnteringItem:(NSString *)item;
@end

@interface ChooseCar : UIViewController
@property (nonatomic, weak) id <ChooseCarDelegate> delegate;
@end

<强> ChooseCar.m

#import "ChooseCar.h"

@interface ChooseCar ()
@end

@implementation ChooseCar

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

//    NSString *itemToPassBack = @"Pass this value back to ViewControllerA";
//    [self.delegate addItemViewController:self didFinishEnteringItem:itemToPassBack];

}

- (void)didReceiveMemoryWarning {
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}
- (IBAction)backButtonClicked:(id)sender {
    NSString *itemToPassBack = @"Pass this value back to ViewControllerA";
   [self.delegate addItemViewController:self didFinishEnteringItem:itemToPassBack];
}

/*
 #pragma mark - Navigation

 // In a storyboard-based application, you will often want to do a little preparation before navigation
 - (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender {
 // Get the new view controller using [segue destinationViewController].
 // Pass the selected object to the new view controller.
 }
 */

@end

iOS presentViewController委托返回黑屏

2 个答案: