Ios 带定位点的自动布局页边距

所以，我认为以下是等效的

# This is how I usually do
contentView.leftAnchor.constraint(equalTo: leftAnchor, constant: 5).isActive = true
contentView.topAnchor.constraint(equalTo: topAnchor, constant: 5).isActive = true
contentView.rightAnchor.constraint(equalTo: rightAnchor, constant: -5).isActive = true
contentView.bottomAnchor.constraint(equalTo: bottomAnchor, constant: -5).isActive = true

# This is what I tried. I expected the same result..
layoutMargins = UIEdgeInsets(top: 5, left: 5, bottom: 5, right: 5)
contentView.leftAnchor.constraint(equalTo: layoutMarginsGuide.leftAnchor).isActive = true
contentView.topAnchor.constraint(equalTo: layoutMarginsGuide.topAnchor).isActive = true
contentView.rightAnchor.constraint(equalTo: layoutMarginsGuide.rightAnchor).isActive = true
contentView.bottomAnchor.constraint(equalTo: layoutMarginsGuide.bottomAnchor).isActive = true

虽然我似乎错了。如何使用边距、约束和锚定在containerView和父级之间获得5个边距？

Objective-C:

[contentView.leftAnchor constraintEqualToAnchor:contentView.superview.leftAnchor constant:5].active = YES;
[contentView.rightAnchor constraintEqualToAnchor:contentView.superview.rightAnchor constant:5].active = YES;
[contentView.topAnchor constraintEqualToAnchor:contentView.superview.topAnchor constant:5].active = YES;
[contentView.bottomAnchor constraintEqualToAnchor:contentView.superview.bottomAnchor constant:5].active = YES;

Swift 3：

contentView.leftAnchor.constraint(equalTo: contentView.superview?.leftAnchor, constant: 5).isActive = true
contentView.rightAnchor.constraint(equalTo: contentView.superview?.rightAnchor, constant: 5).isActive = true
contentView.topAnchor.constraint(equalTo: contentView.superview?.topAnchor, constant: 5).isActive = true
contentView.bottomAnchor.constraint(equalTo: contentView.superview?.bottomAnchor, constant: 5).isActive = true

---

我通过阅读以下问题找到了解决方案：

从

init

设置

layoutMargins

时，似乎存在问题

尽管如此，我没有在

viewdimovetosuperview

中设置

layoutMargins

，而是将其放在

updateConstraints

中，这也很有效

因此，代码现在是：

override init(frame: CGRect) {
    super.init(frame: frame)
    contentView.leftAnchor.constraint(equalTo: layoutMarginsGuide.leftAnchor).isActive = true
    contentView.topAnchor.constraint(equalTo: layoutMarginsGuide.topAnchor).isActive = true
    contentView.rightAnchor.constraint(equalTo: layoutMarginsGuide.rightAnchor).isActive = true
    contentView.bottomAnchor.constraint(equalTo: layoutMarginsGuide.bottomAnchor).isActive = true
}

override func updateConstraints() {
    super.updateConstraints()
    layoutMargins = UIEdgeInsets(top: 5, left: 5, bottom: 5, right: 5)
}

其效果与：

contentView.leftAnchor.constraint(equalTo: leftAnchor, constant: 5).isActive = true
contentView.topAnchor.constraint(equalTo: topAnchor, constant: 5).isActive = true
contentView.rightAnchor.constraint(equalTo: rightAnchor, constant: -5).isActive = true
contentView.bottomAnchor.constraint(equalTo: bottomAnchor, constant: -5).isActive = true

---

似乎在

updateConstraints（）

中设置

layoutMargins

是可行的，但需要注意以下几点：

override func updateConstraints() {
    super.updateConstraints()
    layoutMargins = UIEdgeInsets(top: 8, left: 8, bottom: 8, right: 8)
}

上述代码将无法更新边距，因为新值与系统默认值相同。为了安全起见，首先将边距重置为零：

override func updateConstraints() {
    super.updateConstraints()
    layoutMargins = .zero
    layoutMargins = UIEdgeInsets(top: 8, left: 8, bottom: 8, right: 8)
}

---

另外，如果您的目标是将初始边距设置为

.zero

，那么最好先将其设置为非零值，以确保视图收到更改通知。

如果您阅读了问题，您会发现这正是您所说的我现在正在做的事情，我想知道如何让它与layoutMarginGuides一起工作，而不是确定它在这种情况下是否重要，但一般来说，应该在实现结束时调用

super.updateConstraints（）

：