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如何使用相对点以编程方式定位视图?

cocoa-touch iphone

Steve Madsen · 技术社区 · 14 年前

当超级视图的边界未知时,相对于超级视图的大小定位视图的最佳方法是什么?

如果可能的话,我尽量避免硬编码坐标。也许这是愚蠢的,如果是这样,这是一个完全可以接受的答案。

我在使用自定义UI时遇到过很多次。最近的一个例子是我试图替换 UINavigationItem 带有自定义视图的纯文本标题。我想让那个视图填满superview,但是另外,我想 UIActivityIndicatorView

- (void) viewDidLoad
{
    [super viewDidLoad];

    customTitleView = [[UIView alloc] initWithFrame:CGRectZero];
    customTitleView.autoresizingMask = UIViewAutoresizingFlexibleHeight | UIViewAutoresizingFlexibleWidth;

    titleLabel = [[UILabel alloc] initWithFrame:CGRectZero];
    titleLabel.autoresizingMask = UIViewAutoresizingFlexibleHeight | UIViewAutoresizingFlexibleWidth;
    titleLabel.lineBreakMode = UILineBreakModeWordWrap;
    titleLabel.numberOfLines = 2;
    titleLabel.minimumFontSize = 11.0;
    titleLabel.font = [UIFont systemFontOfSize:17.0];
    titleLabel.adjustsFontSizeToFitWidth = YES;
    [customTitleView addSubview:titleLabel];

    spinnerView = [[UIActivityIndicatorView alloc] initWithActivityIndicatorStyle:UIActivityIndicatorViewStyleWhite];
    spinnerView.center = CGPointMake(customTitleView.bounds.size.width - (spinnerView.bounds.size.width / 2) - 2,
                                     customTitleView.bounds.size.height / 2);
    spinnerView.hidesWhenStopped = YES;
    [customTitleView addSubview:spinnerView];

    self.navigationItem.titleView = customTitleView;
    [customTitleView release];
}

customTitleView.bounds 仍然是零。自动调整大小掩码还没有机会完成它的工作,但是我非常想要这些值,这样我就可以计算其他子视图(这里是活动指示器)的相对位置。

这不难看吗?

1 回复 | 直到 14 年前

cduhn 14 年前

customTitleView.bounds的宽度和高度为零的唯一原因是您已经使用CGRectZero对其进行了初始化。可以使用任何非零大小初始化视图,然后根据该任意大小定义其子视图。只要您正确定义了子视图的自动调整大小行为,当超级视图的框架在运行时发生变化时,它们的布局就会得到适当的调整。

例如:

- (void) viewDidLoad
{
    [super viewDidLoad];

    customTitleView = [[UIView alloc] initWithFrame:CGRectMake(0.0f, 0.0f, 100.0f, 100.0f)];
    customTitleView.autoresizingMask = UIViewAutoresizingFlexibleHeight | UIViewAutoresizingFlexibleWidth;

    titleLabel = [[UILabel alloc] initWithFrame:customTitleView.bounds];
    titleLabel.autoresizingMask = UIViewAutoresizingFlexibleHeight | UIViewAutoresizingFlexibleWidth;
    titleLabel.lineBreakMode = UILineBreakModeWordWrap;
    titleLabel.numberOfLines = 2;
    titleLabel.minimumFontSize = 11.0;
    titleLabel.font = [UIFont systemFontOfSize:17.0];
    titleLabel.adjustsFontSizeToFitWidth = YES;
    [customTitleView addSubview:titleLabel];
    [titleLabel release];

    spinnerView = [[UIActivityIndicatorView alloc] initWithActivityIndicatorStyle:UIActivityIndicatorViewStyleWhite];
    spinnerView.center = CGPointMake(customTitleView.bounds.size.width - (spinnerView.bounds.size.width / 2) - 2,
                                     customTitleView.bounds.size.height / 2);
    spinnerView.autoresizingMask = UIViewAutoresizingFlexibleLeftMargin | UIViewAutoresizingFlexibleTopMargin | UIViewAutoresizingFlexibleBottomMargin;
    spinnerView.hidesWhenStopped = YES;
    [customTitleView addSubview:spinnerView];
    [spinnerView release];

    self.navigationItem.titleView = customTitleView;
    [customTitleView release];
}