Question

有人可以看看我出错了吗？

我有一个名为Object的对象，它有一个NSString属性。

然后我有一个带有按钮的MainViewController。按钮以编程方式创建，并在运行时添加。

当你点击这个按钮时，它应该将对象的值设置为String，并将其传递给下一个ViewController。

我设法设置Object属性的值，但是当我调用该值来传递它时，它被设置为null。我尝试了很多不同的解决方案，但似乎没有任何效果。谁能看到我的问题所在？我已在下面添加了所有相关代码

Object.h

@interface Object : NSObject
@property (nonatomic, strong) NSString *content;

Object.m

#import "Object.h"
@implementation Object
@synthesize content;

然后在MianViewController中创建按钮并设置Object属性的值 MainViewController.h

@interface MainViewController : UIViewController
@property (nonatomic, strong) UIButton *myButton;

MainViewController.m

#import "MainViewController.h"
#import "SecondaryViewController.h"
#import "Object.h"
.
.
@synthesize myButton;

- (void)viewDidLoad
{
    [super viewDidLoad];

    myButton = [UIButton buttonWithType:UIButtonTypeCustom];
    myButton.tag = 1;
    myButton.frame = CGRectMake(20, 140, 280.f, 40.f);
    UIImage *airButton = [UIImage imageNamed:@"gettingHereByAirButton.png"];
    [myButton setBackgroundImage:airButton forState:UIControlStateNormal];
    [self.view addSubview:myButton];
    [myButton addTarget:self action:@selector(myButtonClicked) forControlEvents:UIControlEventTouchUpInside];
}

- (void) myButtonClicked
{
    [self performSegueWithIdentifier:@"mySegue" sender:self];
}

- (void) prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender
{
    NSLog(@"Getting Here...");

    Object *object = [[Object alloc] init];
    object.content = @"This is the content of the Object";

    NSLog(@"Content of Object Set To: %@", object.content);

    SecondaryViewController *vc;
    vc.object = object;

    NSLog(@"Object: %@", object);
    NSLog(@"Object.content: %@", object.content);
    NSLog(@"ViewController.object.content: %@", vc.object.content);

    NSLog(@"Just Did Stuff...");
}

SecondaryViewController，其中标签应设置为Object String的标签 SecondaryViewController.h

#import "Object.h"

@interface SecondaryViewController : UIViewController
@property (weak, nonatomic) IBOutlet UILabel *contentLabel;
@property (nonatomic, strong) Object *object;

SecondaryViewController.m

@synthesize object;
@synthesize contentLabel;

- (void)viewDidLoad
{
    [super viewDidLoad];

    NSLog(@"Content of Object: %@", object.content);

    self.contentLabel.text = object.content;
}

当应用程序运行HERE

时，最后屏幕抓取我的NSLog

Answer 1

SecondaryViewController *vc;

应该是

SecondaryViewController *vc = (SecondaryViewController *)segue.destinationViewController;

对象属性设置为null

1 个答案: