Question

我有这样的场景：我是Xcode的新手并且也完成了样本。实际上我使用的是SplitView Controller，一切正常，但是当涉及到细节View控制器时，我的意思是在带有两个ViewControllers的Navigation Cotroller中。

因为我只是使用了一个“Picker”来获取位置，当我按下获取位置时，它就转向第二个视图控制器，但是在这里我没有检索到这个值。这是一段代码

// ViewController1.h

#import "QuerySubmission.h"

@interface MDDetailViewController : UIViewController <UISplitViewControllerDelegate>
{
    IBOutlet UIPickerView *pickerView;
    NSArray *pickerViewArray;
    NSString *setLocation;


}

@property (nonatomic, retain) NSArray *pickerViewArray;
@property (weak, nonatomic) IBOutlet UIPickerView *pickerView;
@property(nonatomic,retain) NSString *setLocation;

@property (strong, nonatomic) id detailItem;

@property (strong, nonatomic) IBOutlet UILabel *detailDescriptionLabel;

- (IBAction)getLocation:(id)sender;

@end

// ViewController1.m

 - (IBAction)getLocation:(id)sender {
    int selectedIndex = [self.pickerView selectedRowInComponent:0];
    NSString *message = [NSString stringWithFormat:@"Selected Location: %@",[pickerViewArray objectAtIndex:selectedIndex]];
    UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Alert" message:message delegate:self cancelButtonTitle:@"OK" otherButtonTitles:nil];
    [alert show];

    QuerySubmission *obj = [[QuerySubmission alloc] initWithNibName:@"QuerySubmission" bundle:nil];
    obj.location=[pickerViewArray objectAtIndex:selectedIndex];

    //NSLog(@"loc %@", [ pickerViewArray objectAtIndex:selectedIndex]);
    //[ pickerViewArray objectAtIndex:selectedIndex];
}

我在这里获取位置列表并检索

// ViewController2.h

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

@interface QuerySubmission : UIViewController <UISplitViewControllerDelegate>
{
    NSString *location;
}

@property(nonatomic,retain) NSString *location;
- (IBAction)querySubmit:(id)sender;

@end

但是想转移到另一个控制器。它只是打印“null”。我是SplitView Controller的新手。我做错了什么，或者需要在“代表”“”声明什么？请做到需要

Answer 1

最好将AppDelegate用于此类任务！

在@property(nonatomic,retain) NSString *location;文件中声明属性AppDelegate.h。

重写getLocation:方法，如：

- (IBAction)getLocation:(id)sender
{
    int selectedIndex = [self.pickerView selectedRowInComponent:0];
    NSString *message = [NSString stringWithFormat:@"Selected Location: %@",[pickerViewArray objectAtIndex:selectedIndex]];
    UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Alert" message:message delegate:self cancelButtonTitle:@"OK" otherButtonTitles:nil];
    [alert show];
     [[[UIApplication sharedApplication] delegate] setLocation:(NSString *)[pickerViewArray objectAtIndex:selectedIndex]];
}

在QuerySubmission中，您可以使用以下方式访问该位置：

[[[UIApplication sharedApplication] delegate] location];

Answer 2

如果您正在从一个控制器到另一个控制器执行segue，传递值就像在ViewController1实现中添加这些代码一样简单：

- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender
{
    QuerySubmission * viewController2 = segue.destinationViewController;
    if(viewController2)
    {
        viewController2.location=[pickerViewArray objectAtIndex:selectedIndex];
    }
}

而我自己，我尝试将填充变量最小化到app委托中，这实际上应该主要用于UIApplicationDelegate类型的东西，比如正在暂停的应用程序等。

在SplitView控制器中的两个视图控制器之间传递VALUE

2 个答案: