Question

我正在尝试将数据从表视图控制器传递到详细视图控制器。我的表的每个条目都可以正常工作，除了一个。这是prepareForSegue方法：

- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender{
    if ([[segue identifier] isEqualToString:@"showDetails"]) {
        NSIndexPath *indexPath = [[self tableView] indexPathForSelectedRow];
        NSDictionary *notification = [[self notifications] objectAtIndex:[indexPath row]];
        NRDetailViewController *destViewController = [segue destinationViewController];
        [destViewController setDate:[notification objectForKey:@"date"]];
        [destViewController setFrom:[notification objectForKey:@"from"]];
        [destViewController setIden:[notification objectForKey:@"identifier"]];
        [destViewController setPriority:[notification objectForKey:@"priority"]];
        [destViewController setSubject:[notification objectForKey:@"subject"]];
        [destViewController setMessage:[notification objectForKey:@"text"]];

    }
}

这是我的详细视图界面：

#import <UIKit/UIKit.h>

@interface NRDetailViewController : UIViewController

@property (weak, nonatomic) IBOutlet UITextField *dateField;
@property (weak, nonatomic) IBOutlet UITextField *fromField;
@property (weak, nonatomic) IBOutlet UITextField *idenField;

@property (weak, nonatomic) IBOutlet UITextField *prioField;
@property (weak, nonatomic) IBOutlet UITextField *subjectField;
@property (weak, nonatomic) IBOutlet UITextView *messageView;


@property (copy, nonatomic) NSString *date;
@property (copy, nonatomic) NSString *from;
@property (copy, nonatomic) NSString *iden;
@property (copy, nonatomic) NSString *priority;
@property (copy, nonatomic) NSString *subject;
@property (copy, nonatomic) NSString *message;


@end

这是详细视图的实现文件：

#import "NRDetailViewController.h"

@interface NRDetailViewController ()

@end

@implementation NRDetailViewController

- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
    self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
    if (self) {
        // Custom initialization
    }
    return self;
}

- (void)viewDidLoad
{
    [super viewDidLoad];
    [[self dateField] setText:[self date]];
    [[self fromField] setText:[self from]];
    [[self idenField] setText:[self iden]];
    [[self prioField] setText:[self priority]];
    [[self subjectField] setText:[self subject]];
    [[self messageView] setText:[self message]];



}

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

@end

我在将idenField的文本设置为iden的文本时遇到问题。我添加了一个异常断点，并且确实在此行发生了异常：

[[self idenField] setText:[self iden]];

此时，我已经打印了[self iden]的值，它甚至包含了我想传递的内容，所以我完全不知道问题是什么，因为正如我所说的，所有其他字段都在工作他们应该这样做。

抛出的异常是：

2013-08-07 22:28:20.539 NotificationReader[1214:11303] -[__NSCFNumber length]: unrecognized selector sent to instance 0x7587a00

非常感谢任何帮助。

Answer 1

看起来像：

[destViewController setIden:[notification objectForKey:@"identifier"]];

返回NSNumber而不是NSString。您可以尝试用以下代码替换该行：

[destViewController setIden:[(NSNumber*)[notification objectForKey:@"identifier"] stringValue]];

Answer 2

您正在某处传递NSNumber而不是NSString。

Answer 3

要设置文字，iden必须为NSString。当您从NSDictionary获取对象时，它是NSNumber。

试试这个：

[destViewController setIden:(NSString *)[notification objectForKey:@"identifier"]];

或将iden属性更改为NSNumber，然后

[[self idenField] setText:[NSString stringWithFormat:@"%d", [self iden]]];

[__NSCFNumber length]：发送到实例的无法识别的选择器

3 个答案: