iOS NSInvalidArgumentException，无法识别的选择器发送到实例

Question

我是 iOS 的新手，正在学习教程。现在，我有这段代码:

- (void)viewWillAppear:(BOOL)animated
{
    // [super viewWillAppear:animated];
    if(self.firstName)
    {
        NSLog(@"%@",self.firstName);
        self.textFieldFirstName.text = self.firstName;
    }
}

首先，如上所述，我不得不注释掉对 super 的调用 - 该应用不想启动。第二:任务 self.textFieldFirstName.text = self.firstName;使用 SIGABORT 使应用程序崩溃并输出:

2014-10-13 11:50:19.631 PersonalStoryboard[1451:60b] firstName = John
2014-10-13 11:50:19.636 PersonalStoryboard[1451:60b] John
2014-10-13 11:50:19.636 PersonalStoryboard[1451:60b] -[UIView setText:]: unrecognized selector sent to instance 0x8f97470
2014-10-13 11:50:19.639 PersonalStoryboard[1451:60b] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[UIView setText:]: unrecognized selector sent to instance 0x8f97470'
*** First throw call stack:

为什么？提前致谢。

---

谢谢大家。文件1:

//

#import "FirstNameEditViewController.h"

@interface FirstNameEditViewController ()
@property (strong, nonatomic) IBOutlet UITextField *textFieldFirstName;
@end

@implementation FirstNameEditViewController

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

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

- (void)didReceiveMemoryWarning
{
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}
- (void)viewWillAppear:(BOOL)animated
{
    // [super viewWillAppear:<#animated#>];
    if(self.firstName)
    {
        NSLog(@"%@",self.firstName);
        self.textFieldFirstName.text = self.firstName;
    }
}

@结束

文件2:

#define LogPretty NSLog(@"LogPretty:%s %d %s",__FILE__,__LINE__,__PRETTY_FUNCTION__);
#import "PersonalDetailViewController.h"
#import "FirstNameEditViewController.h"
#import "Person.h"

@interface PersonalDetailViewController ()

  @property (strong, nonatomic) IBOutlet UIButton *buttonFirstName;
  @property (strong, nonatomic) IBOutlet UIButton *buttonName;
  @property (strong, nonatomic) IBOutlet UIButton *buttonAge;
  @property (strong, nonatomic) IBOutlet UIButton *buttonJob;
  @property (strong, nonatomic) IBOutlet UIButton *buttonSalary;

@end

@implementation PersonalDetailViewController
{
    Person *person;
 }
- (void)viewDidLoad
{
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.
    person = [[Person alloc] init];
    [self showPerson];
}

- (void)showPerson
{
    LogPretty
    /*
     IT CRASHES HERE !!!

    [self.buttonFirstName setTitle:person.firstName forState:UIControlStateNormal];
    [self.buttonName setTitle:person.name forState:UIControlStateNormal];
    [self.buttonJob setTitle:person.job forState:UIControlStateNormal];
    [self.buttonAge setTitle:person.age forState:UIControlStateNormal];
    [self.buttonSalary setTitle:person.salary forState:UIControlStateNormal];
    */
}

- (void)didReceiveMemoryWarning
{
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}
- (IBAction)buttonFirstNameTouched:(id)sender {
    [self performSegueWithIdentifier:@"firstNameEditSegue" sender:(self)];
}
- (IBAction)buttonNameTouched:(id)sender {
}
- (IBAction)buttonAgeTouched:(id)sender {
}
- (IBAction)buttonJobTouched:(id)sender {
}
- (IBAction)buttonSalaryTouched:(id)sender {
}
- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender
{
    NSLog(@"identifier = %@",segue.identifier);

    if([segue.identifier isEqualToString:@"firstNameEditSegue"])
    {
        NSLog(@"firstName = %@",person.firstName);
        FirstNameEditViewController *editController = segue.destinationViewController;
        editController.firstName = person.firstName;
    }
}
@end

最后是人:

#define LogPretty NSLog(@"%s %d %s",__FILE__,__LINE__,__PRETTY_FUNCTION__);
#import "Person.h"

  @implementation Person

- (id) init
{
    LogPretty
    self = [super init];
    if(self)
    {
        self.firstName = @"John";
        self.name = @"Brown";
        self.job = @"Developer";
        self.age = 35;
        self.salary = 35000;
    }
    return self;
}
@end

我将非常感谢您的帮助

Answer 1

好的，首先，对 super 的调用很重要，如果您必须将其注释掉以使您的代码正常工作，则其他地方也一定有问题。它很重要，因为它负责在您的类的父类(super class) 中执行操作，即UIViewController。此方法是 UIViewController 生命周期的一部分。

您的实际问题来自于您想要在 UIView 类型的对象上调用方法 setText:，消息表明了这一点: -[UIView setText:]: 无法识别的选择器发送到实例 0x8f97470。如果你看一下 documentation of the UIView class ，您会看到它没有公开一个名为 setText: 的方法(或者更确切地说，它没有 text 属性以及它的 setter 方法) .这就是应用程序崩溃的原因。

我假设您想在 UILabel 或 UITextField 上执行此操作。我还可以想象的是，您实际上已经在使用这些类中的任何一个，但它不起作用，因为您评论了 viewWillAppear。在那种情况下，您应该显示更多代码和 Storyboard设置，否则将很难找到您的问题或给您进一步的指导。

最后的简短说明，这种初始化最好在 viewDidLoad 而不是 viewWillAppear 中完成。