Question

我想在滚动视图中添加标签。这是在主控制器中完成的。但是，当我执行以下操作时，标签将覆盖滚动视图的内容。我希望标签完全位于顶部，然后是其余的滚动视图内容。

    UILabel *label = [[UILabel alloc]initWithFrame:CGRectMake(0, 0, self.contentView.frame.size.width, 80)];
    label.backgroundColor = [UIColor greenColor];
    label.text = @"Testing";

    [self.scrollView addSubview: label];
    [self.scrollView setNeedsDisplay];

Answer 1

不幸的是，还有一些以编程方式执行此操作。我强烈建议您将此标签添加到您的xib或故事板中，而不是以编程方式执行此操作，但如果这不是任何理由，那么您只能执行一项操作。你需要迭代你的scrollView的子项并稍微向下推动每个下来为你的新标签腾出空间，然后在scrollView的顶部设置标签。

非常简单的例子，这可能无法完美运行，因此您需要根据需要调整它。

// Set the amount of y padding to push each subview down to make room at the top for the new label
CGFloat yPadding = 80.0f;
CGFloat contentWidth = CGRectGetWidth(self.contentView.frame);
UILabel* label = [[UILabel alloc] initWithFrame:(CGRect){CGPointZero, contentWidth, 44.0f}];
label.text = @"Testing";

// Iterate over each subview and push it down by the amount set in yPadding. Also, check for the subview with the lowest y value and set that as your labels y so that it is at the top of the scrollView.
for (UIView* subview in self.scrollView.subviews) {
    CGRect subviewFrame = subview.frame;
    CGFloat currentLabelY = CGRectGetMinY(label.frame);
    // Set the labels y based off the subview with the lowest y value
    if (currentLabelY == 0.0f || (currentLabelY > CGRectGetMinY(subviewFrame))) {
        CGRect labelFrame = label.frame;
        labelFrame.origin.y = subviewFrame.origin.y;
        label.frame = labelFrame;
    }
    // Push the subview down by the amount set in yPadding
    subviewFrame.origin.y += yPadding;
    subview.frame = subviewFrame;
}
// Finally, add the label as a subView of the scrollView
[self.scrollView addSubview:label];

Answer 2

您应该将标签添加为scrollview的子视图：

[self.scrollView addSubview:label]

在iOS中向滚动视图添加标签

2 个答案: