ios - 字符串赋值不起作用

Question

我想在两个 viewcontroller 之间传递一个字符串，但总是 (null)

我的代码

GridViewController.h

 #import <UIKit/UIKit.h>

 @interface GridViewController : UIViewController {

 }

 @property (nonatomic, strong)UILabel * labelTitle;

 @end

ViewController.m

-(void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:
    (NSIndexPath *)indexPath{

       NSString *currow =[self.mutableArray objectAtIndex:indexPath.row];
       NSLog(@"the string is %@", currow);
       //the string is Grappe, Brandy and Cognac

       GridViewController * grid = [[GridViewController alloc]initWithNibName:@"GridViewController~iPhone" bundle:nil];

       grid.labelTitle.text = currow;

       NSLog(@"the string is %@", grid.labelTitle.text);
       //the string is (null)

       NSLog(@"the string is  %@", currow);
       //the string is Grappe, Brandy and Cognac

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

 }

Answer 1

labelTtitle 是 GridViewController 的 GUI 元素，当您尝试在其他类中访问时它不会获得任何值，您最好尝试创建一个 GridViewController 中的 NSString 并将值分配给另一个类中的此字符串，但是当您为 GridViewController 加载 viewDidLoad 时然后像这样将此字符串分配给您的标签

-(void)viewDidLoad{

    [super viewDidLoad]; 
    self.labelTitle.text=self.stringYouCreated;

}

在 ViewController.m 中，将值分配给您在 GridViewcontroller 中创建的字符串属性，如下所示

   grid.stringYouCreated = currow;