Objective c UILabel不显示

我正试图通过编程方式添加UILabel（我用IB完成了这项工作，而且效果很好）。但是我不知道为什么它没有出现。。我通过编程添加了一个按钮，效果很好。我希望按钮用随机引用更新标签。怎么了

.h文件：

@interface SecondViewController : UIViewController
{
    NSArray *citatDatabas;

}

@property (weak, nonatomic) IBOutlet UIButton *helloButton;
@property (weak, nonatomic) IBOutlet UIButton *citatKnapp;
@property (weak, nonatomic) IBOutlet UILabel *label1;

- (void)helloButtonPressed;
- (IBAction)citatKnappPressed:(id)sender;

@end

实施：

@implementation SecondViewController
@synthesize helloButton, citatKnapp, label1;

- (void)loadView {
    [super loadView]; 
citatDatabas = [NSArray arrayWithObjects:
                    [NSString stringWithFormat:@"%@", @"People ask me, would you rather be feared or loved, um easy, I want people to be afriad of how much they love me - Michael Scott" ],
                    [NSString stringWithFormat:@"%@", @"You miss 100% of all the shoots you dont take - Wayne Greatsky - Michael Scott" ],
                    [NSString stringWithFormat:@"%@", @"DONT PANIC - hitchhiker's guide to the galaxy" ],
                    [NSString stringWithFormat:@"%@", @"Give someone a mask and they'll show their true face - Oscar Wilde" ],
                    [NSString stringWithFormat:@"%@", @"Given enough time, hydrogen starts to wonder where it came from, and where it is going" ],
                    [NSString stringWithFormat:@"%@", @"You have just begun reading the sentence you just finished reading" ],
                    nil];



    self.citatKnapp = [UIButton buttonWithType:UIButtonTypeRoundedRect];
    self.citatKnapp.frame = CGRectMake(98, 162, 124, 37);
    [self.citatKnapp setTitle:@"Tryck för citat" forState:UIControlStateNormal];
    [self.citatKnapp addTarget:self action:@selector(citatKnappPressed:)     forControlEvents:UIControlEventTouchUpInside];

    self.citatKnapp.autoresizingMask = UIViewAutoresizingFlexibleBottomMargin | UIViewAutoresizingFlexibleLeftMargin | UIViewAutoresizingFlexibleRightMargin;

    [self.view addSubview:self.citatKnapp];

    self.label1 = [[UILabel alloc]initWithFrame:CGRectMake(20, 71, 200, 83)];

    self.label1.frame = CGRectMake(20, 71, 200, 83);
    self.label1.text = @"hej";
    self.label1.backgroundColor = [UIColor greenColor];
    [self.view addSubview:self.label1];


}

- (IBAction)citatKnappPressed:(id)sender{

    self.label1.text = [citatDatabas objectAtIndex:
                  (random() % [citatDatabas count])];
}

@end

---

原因是在loadView中，您的视图未初始化。是否通过XIB/故事板连接

如果没有,

只需将视图初始化为方法中添加标签的第一行

self.view = [[UIView alloc]initWithFrame:CGRectMake(0,0,320,480)];

---

然后写下你剩下的代码

你的标签将被释放，使用

@property（强，非原子）IBOutlet UILabel*label1

如果在分配label1后在任何一行上放置断点，您将看到label1为nil
您是否尝试在UILabel上设置不同的
帧
，以确保它不仅仅是定位错误？该标签是一个IBOutlet，因此我是否假设您已在interface builder中创建了它？如果是这样，请尝试删除
self.label1=[[UILabel alloc]initWithFrame:CGRectMake（20,71,200,83）]
@nspostwenidle no我通过编程添加了它，删除了IBOutlet，但现在我明白它的作用了！：）这不会导致标签不可见，因为他正在将其添加到视图中，并且视图始终保持对其子视图的强引用。当使用弱引用时，它将在这一行之后立即释放：
self.label1=[[UILabel alloc]initWithFrame:CGRectMake（20,71,200,83）]因此，当他将其添加到视图中时，它将已经是零。准确地说，这确实解决了它：O但我不明白为什么/如何？弱引用只会持续，只要有不同的东西将其保持为强引用。如果你创建一个对象，只把它放在一个弱变量中，它将无法在这一行代码中生存。但是当我用IB在故事板中创建同一个标签时，它显示@property（弱，非原子）IBUILabel*标签；这样行吗？这就是为什么我不理解它，我想它是在IB故事板中初始化的