在这种情况下,如何重用 UIPickerView 中的视图?
How do I reuse a view inside UIPickerView in this case?
似乎很多人只是 return 一个 UILabel,但在我的例子中,我向视图添加了一个标签。观点永远不是零。这是 UIPickerView 的另一种用法,因为我将其组件旋转 90 度并使其横向滚动而不是上下滚动。
func pickerView(_ pickerView: UIPickerView, viewForRow row: Int, forComponent component: Int, reusing view: UIView?) -> UIView {
if view == nil {
let customWidth = 300
let customHeight = 300
let view = UIView(frame: CGRect(x:0, y:0, width:customWidth, height:customHeight))
let label = UILabel(frame:CGRect(x:0, y:0, width:customWidth, height:customHeight))
if let filter = filters.first(where: {[=10=].pickerViewRowIndex == row}) {
var leading = ""
if appPurchased == false && filter.requiresPurchase == true { leading = "" }
label.text = "\(leading)\(filter.nameStr)"
}
label.textColor = UIColor.black
label.font = UIFont(name:"HelveticaNeue-Bold", size: 18.0)
label.textAlignment = .center
view.addSubview(label)
view.transform = CGAffineTransform(rotationAngle: 90 * (.pi/180))
label.layer.masksToBounds = false
return view
}else{
print("not nil") // console never prints this line
}
guard let reusedView = view else {
assertionFailure("pickerView label view container never set")
return view!
}
return reusedView
}
The view is never not nil.
正确。文档是错误的。实际上没有在选择器视图中重用视图这样的事情 viewForRow
。您总是需要创建一个新视图并 return 它。
似乎很多人只是 return 一个 UILabel,但在我的例子中,我向视图添加了一个标签。观点永远不是零。这是 UIPickerView 的另一种用法,因为我将其组件旋转 90 度并使其横向滚动而不是上下滚动。
func pickerView(_ pickerView: UIPickerView, viewForRow row: Int, forComponent component: Int, reusing view: UIView?) -> UIView {
if view == nil {
let customWidth = 300
let customHeight = 300
let view = UIView(frame: CGRect(x:0, y:0, width:customWidth, height:customHeight))
let label = UILabel(frame:CGRect(x:0, y:0, width:customWidth, height:customHeight))
if let filter = filters.first(where: {[=10=].pickerViewRowIndex == row}) {
var leading = ""
if appPurchased == false && filter.requiresPurchase == true { leading = "" }
label.text = "\(leading)\(filter.nameStr)"
}
label.textColor = UIColor.black
label.font = UIFont(name:"HelveticaNeue-Bold", size: 18.0)
label.textAlignment = .center
view.addSubview(label)
view.transform = CGAffineTransform(rotationAngle: 90 * (.pi/180))
label.layer.masksToBounds = false
return view
}else{
print("not nil") // console never prints this line
}
guard let reusedView = view else {
assertionFailure("pickerView label view container never set")
return view!
}
return reusedView
}
The view is never not nil.
正确。文档是错误的。实际上没有在选择器视图中重用视图这样的事情 viewForRow
。您总是需要创建一个新视图并 return 它。