如何缩放容器UIView而不影响内部子视图？附代码实现

我懂你的需求：长按缩放蓝色容器视图时，中间的红色视图要保持原尺寸不变。目前的问题在于，当你给viewIWantToScale应用CGAffineTransform缩放时，它的子视图viewIDontWantToScale会自动继承这个变换——哪怕你设置了autoresizesSubviews = false也没用，因为transform是视图层级的几何变换，和自动布局的 autoresizing 机制完全是两回事。

下面给你两种可行的解决方案：

方案一：将内部视图移到容器视图的同级（推荐） #

这种方式最直接，把红色视图从蓝色视图的子视图改成父视图的同级，再用约束绑定到蓝色视图的中心和固定尺寸。这样蓝色视图缩放时，红色视图完全不受影响，因为它不在蓝色视图的层级里。

修改后的完整代码示例：

let viewIWantToScale = UIView()
let viewIDontWantToScale = UIView()

private func configureViewIWantToScale() {
    let tabDetector = UILongPressGestureRecognizer(target: self, action: #selector(gestureAction(_:)))
    viewIWantToScale.translatesAutoresizingMaskIntoConstraints = false;
    viewIWantToScale.addGestureRecognizer(tabDetector)
    // 红色视图不再是子视图，这个设置可以去掉
    // viewIWantToScale.autoresizesSubviews = false
    view.addSubview(viewIWantToScale)
    NSLayoutConstraint.activate([
        viewIWantToScale.centerYAnchor.constraint(equalTo: view.centerYAnchor),
        viewIWantToScale.centerXAnchor.constraint(equalTo: view.centerXAnchor),
        viewIWantToScale.widthAnchor.constraint(equalToConstant: 300),
        viewIWantToScale.heightAnchor.constraint(equalToConstant: 300)
    ])
    viewIWantToScale.backgroundColor = .blue
}

private func configureViewIDontWantToScale() {
    viewIDontWantToScale.translatesAutoresizingMaskIntoConstraints = false;
    viewIDontWantToScale.isUserInteractionEnabled = false
    view.addSubview(viewIDontWantToScale) // 和蓝色视图同级添加到父视图
    NSLayoutConstraint.activate([
        viewIDontWantToScale.centerYAnchor.constraint(equalTo: viewIWantToScale.centerYAnchor),
        viewIDontWantToScale.centerXAnchor.constraint(equalTo: viewIWantToScale.centerXAnchor),
        viewIDontWantToScale.widthAnchor.constraint(equalToConstant: 150),
        viewIDontWantToScale.heightAnchor.constraint(equalToConstant: 150)
    ])
    viewIDontWantToScale.backgroundColor = .red
}

@objc private func gestureAction(_ sender: UILongPressGestureRecognizer) {
    switch sender.state {
    case .began, .changed:
        // 示例缩放1.5倍，你可以根据需求调整倍数
        UIView.animate(withDuration: 1) {
            self.viewIWantToScale.transform = CGAffineTransform(scaleX: 1.5, y: 1.5)
        }
    case .ended, .cancelled:
        // 恢复原尺寸
        UIView.animate(withDuration: 1) {
            self.viewIWantToScale.transform = .identity
        }
    default:
        break
    }
}

方案二：给内部视图应用反向变换（适合必须保留父子层级的场景） #

如果因为某些业务限制，必须把红色视图放在蓝色视图内部，那你可以在蓝色视图缩放的同时，给红色视图应用反向的缩放变换，抵消父视图的缩放效果。

修改后的手势处理代码示例：

@objc private func gestureAction(_ sender: UILongPressGestureRecognizer) {
    let targetScale: CGFloat = 1.5 // 容器视图的目标缩放倍数
    switch sender.state {
    case .began, .changed:
        UIView.animate(withDuration: 1) {
            self.viewIWantToScale.transform = CGAffineTransform(scaleX: targetScale, y: targetScale)
            // 用1/目标倍数做反向缩放，抵消父视图的缩放
            self.viewIDontWantToScale.transform = CGAffineTransform(scaleX: 1/targetScale, y: 1/targetScale)
        }
    case .ended, .cancelled:
        UIView.animate(withDuration: 1) {
            self.viewIWantToScale.transform = .identity
            self.viewIDontWantToScale.transform = .identity
        }
    default:
        break
    }
}

注意：这种方式要确保红色视图的约束是绑定到父视图的中心，这样反向变换后它的位置不会偏移。

内容的提问来源于stack exchange，提问作者Omar Ghanem