为了显示我的按钮和标签，我应该添加什么？

Question

我是 iOS 编程的新手，我正在尝试学习如何在不使用 storyboard 的情况下向视图添加标签和按钮。然而，这对我来说并不顺利。我没有收到任何错误，但运行代码时我的对象都没有显示。

这是我的 .h 文件：

@interface SomeViewController : UIViewController

@property (weak, nonatomic) UILabel *quoteLabel;
@property (weak, nonatomic) UIButton *helloButton;

@end

这是我的 .m 文件中的代码：

- (void)loadView {
    [super loadView];
// Should i override this loadView in order to add more graphical elements? How would i do that?

// Creating a view here which i thought i could add my button and label to. 
// Is this the right way to go or is it unnecessary? 

UIView *contentView = [[UIView alloc] init];
    contentView.backgroundColor = [UIColor whiteColor];
    self.view = contentView;

// Creating my buttonWithType 
// (does this also make my button allocated and initiated or do i need to do that manually?)
// Is this unnecessary considering iOS 7's default buttons is just a text?

self.helloButton = [UIButton buttonWithType:UIButtonTypeRoundedRect];
    self.helloButton.frame = CGRectMake(100.0, 35.0, 120.0, 30.0);
    [self.helloButton setTitle:@"Hello" forState:UIControlStateNormal];
    [self.helloButton addTarget:self
                         action:@selector(helloButtonPressed)
               forControlEvents:UIControlEventTouchUpInside];
    self.helloButton.autoresizingMask = UIViewAutoresizingFlexibleBottomMargin | UIViewAutoresizingFlexibleLeftMargin | UIViewAutoresizingFlexibleRightMargin;

// Try to add this button to the view, but it won't show.
    [contentView addSubview:self.helloButton];

// Same issue for my label object.

    self.quoteLabel.frame = CGRectMake(55.0, 85.0, 210.0, 21.0);
    self.quoteLabel.textAlignment =  NSTextAlignmentCenter;
    self.quoteLabel.textColor = [UIColor whiteColor];
    self.quoteLabel.backgroundColor = [UIColor blackColor];
    self.quoteLabel.font = [UIFont fontWithName:@"System" size:(17.0)];
    self.quoteLabel.text = @"Test";

// Trying to add it to the contentView
    [contentView addSubview:self.quoteLabel];

我非常想知道如何将那些在 .h 中声明为属性的元素添加到视图中。执行以下操作：

UILabel *someLabel = [ [UILabel alloc ] initWithFrame:CGRectMake(55.0, 85.0, 210.0, 21.0) ];
    someLabel.textAlignment =  NSTextAlignmentCenter;
    someLabel.textColor = [UIColor whiteColor];
    someLabel.backgroundColor = [UIColor blackColor];
    someLabel.font = [UIFont fontWithName:@"System" size:(18.0)];
    [contentView addSubview:someLabel];
    someLabel.text = @"Test";

已经可以正常使用了。

Answer 1

// Creating my buttonWithType 
// (does this also make my button allocated and initiated or do i need to do that manually?)
// Is this unnecessary considering iOS 7's default buttons is just a text?

是的，buttonWithType 确实分配并启动了按钮。

我认为按钮有更多的状态，所以它们是不同的。

我没有看到 quoteLabel 的初始化位置。

您可能应该在 .h 文件中使用强引用而不是弱引用，并且您可能必须在向其添加子视图后刷新视图。