适用于VFL的NSLayoutConstraint风格

Question

  

＆＃34，V：| [V（大于=高度）] - 0.0@highPriority-|"

对于VFL以上的约束（NSLayoutConstraint样式）。

也许正在考虑使用greaterThanEqual＆amp;使用UILayoutPriority.defaultHigh的底部约束。

我用过的东西 -

let heightConstraint = NSLayoutConstraint(item: self.view!, attribute: NSLayoutAttribute.height, relatedBy: NSLayoutRelation.greaterThanOrEqual, toItem: nil, attribute: NSLayoutAttribute.notAnAttribute, multiplier: 1, constant: 0)
let bottomConstraint = NSLayoutConstraint(item: self.view!, attribute: NSLayoutAttribute.bottom, relatedBy: NSLayoutRelation.equal, toItem: nil, attribute: NSLayoutAttribute.notAnAttribute, multiplier: 1, constant: 0)
bottomConstraint.priority = .defaultHigh
NSLayoutConstraint.activate([heightConstraint,bottomConstraint]) 

Answer 1

初步设置答案：

<ListView
  stickySectionHeadersEnabled={false}
  scrollEnabled={!this.state.shouldAnimate}
  style={styles.listView}
  enableEmptySections={true}
  dataSource={this.state.dataSource}
  renderSectionHeader = {this.renderSectionHeader}
   renderRow={(data,i) => {
    if(i==1){}
    else if (i==2){}
    .......
   }}
/>

对于给定的VFL：

  

＆＃34，V：| [V（大于=高度）] - 0.0@highPriority-|"

1。 VFL实施：

let parentView = self.view!

let childView = UIView()
childView.backgroundColor = UIColor.lightGray
childView.translatesAutoresizingMaskIntoConstraints = false
parentView.addSubview(childView)

2。 NSLayoutConstraint实现：

上述VFL的let height: CGFloat = 100 let priority: Int = 1000 //VFL (for vertical positioning and height of childView parentView.addConstraints(NSLayoutConstraint.constraints(withVisualFormat: "V:|[v(>=\(height))]-0.0@\(priority)-|", options: [], metrics: nil, views: ["v" : childView])) 等效词是：

NSLayoutConstraint

注意：问题中给定的VFL仅提供let height: CGFloat = 100 //VFL Equivalent: "V:|[v]" let topConstraint = NSLayoutConstraint(item: childView, attribute: .top, relatedBy: .equal, toItem: parentView, attribute: .top, multiplier: 1, constant: 0) //VFL Equivalent: "[v(>=height)]" let heightConstraint = NSLayoutConstraint(item: childView, attribute: .height, relatedBy: .greaterThanOrEqual, toItem: nil, attribute: .notAnAttribute, multiplier: 1, constant: height) //VFL Equivalent: "[v]|" or "[v]-0.0-|" let bottomConstraint = NSLayoutConstraint(item: childView, attribute: .bottom, relatedBy: .equal, toItem: parentView, attribute: .bottom, multiplier: 1, constant: 0) //Adding VFL Equivalent: @priority bottomConstraint.priority = .defaultHigh childView.addConstraint(heightConstraint) parentView.addConstraint(topConstraint) parentView.addConstraint(bottomConstraint) 的位置和高度 对于width，请相应地添加约束。

宽度的VFL示例为：

childView

参考：

• Apple's Autolayout Guide on VFL