Swift - Customize view to show over an empty table cells - ios

Question

I am using Swift 3, Xcode 8.2.
I've been able to create a label to cover the empty table view cells when there are none to display.
My code is below and it is located in the subclass of UITableViewController.
override func numberOfSections(in tableView: UITableView) -> Int {
// if there are scans to display...
if items.count > 0 {
tableView.backgroundView = nil
tableView.separatorStyle = .singleLine
return 1
}
else { // otherwise, return 0, remove cell lines, and display a Label
let rect = CGRect(x: 0,
y: 0,
width: tableView.bounds.size.width,
height: tableView.bounds.size.height)
let noScanLabel: UILabel = UILabel(frame: rect)
noScanLabel.text = "No Scans"
noScanLabel.textColor = UIColor.gray
noScanLabel.font = UIFont.boldSystemFont(ofSize: 24)
noScanLabel.textAlignment = NSTextAlignment.center
tableView.backgroundView = noScanLabel
tableView.separatorStyle = .none
return 0
}
}
Here is the result.
Looks fine. But how, do I make it such that I include another line of text with a downward arrow pointing at the raised center button. Something like "Click here to start a scan"?
I've tried adding new line characters to the noScanLabel.text field but that didn't work out. Any pointers in the right direction would be helpful.

Answer 1

The simple solution is to set numberOfLines to 0 on noScanLabel. This way, the new lines will show.
let noScanLabel: UILabel = UILabel(frame: rect)
noScanLabel.text = "No Scans"
noScanLabel.textColor = UIColor.gray
noScanLabel.font = UIFont.boldSystemFont(ofSize: 24)
noScanLabel.numberOfLines = 0
noScanLabel.textAlignment = NSTextAlignment.center
Note than in such cases, I would recommend, for better maintainability, to actually remove the TableView from the UIViewController (hence not inherit from UITableViewController) and replace it with an empty view when you detect no scans are available. This will make each state more independent of each other and make maintenance easier.

Answer 2

There are a few ways achieve your goal. There is a well known library called DZNEmptyDataSet for handling empty tableviews and collectionviews . https://github.com/dzenbot/DZNEmptyDataSet
The other way would be to create a uiview with your specified rect and then add two labels to that uiview. One would be your noScanLabel and the other would be a label or image containing your arrow. You can set the layout constraints as required so that the arrow appears pointing down.
This code seems to work well. Change constraints if needed
let rect = CGRect(x: 0, y: 0, width: tableview.bounds.size.width, height: tableview.bounds.size.height)
let noDataView = UIView(frame: rect)
let noScanLabel = UILabel()
noScanLabel.text = "No Scans"
noScanLabel.textColor = UIColor.gray
noScanLabel.font = UIFont.boldSystemFont(ofSize: 24)
noScanLabel.textAlignment = NSTextAlignment.center
let arrowLabel = UILabel()
arrowLabel.text = "Add Arrow Image to this label"
arrowLabel.textColor = UIColor.gray
arrowLabel.font = UIFont.boldSystemFont(ofSize: 24)
arrowLabel.textAlignment = NSTextAlignment.center
noScanLabel.widthAnchor.constraint(equalToConstant: 100)
arrowLabel.widthAnchor.constraint(equalToConstant: 50)
noDataView.addSubview(noScanLabel)
noDataView.addSubview(arrowLabel)
arrowLabel.translatesAutoresizingMaskIntoConstraints = false
noDataView.translatesAutoresizingMaskIntoConstraints = false
noScanLabel.translatesAutoresizingMaskIntoConstraints = false
self.tableview.addSubview(noDataView)
noDataView.isHidden = false
noDataView.centerXAnchor.constraint(equalTo: self.tableview.centerXAnchor).isActive = true
noDataView.centerYAnchor.constraint(equalTo: self.tableview.centerYAnchor).isActive = true
noScanLabel.centerXAnchor.constraint(equalTo: noDataView.centerXAnchor).isActive = true
noScanLabel.topAnchor.constraint(equalTo: noDataView.centerYAnchor).isActive = true
arrowLabel.centerXAnchor.constraint(equalTo: noDataView.centerXAnchor).isActive = true
arrowLabel.topAnchor.constraint(equalTo: noScanLabel.bottomAnchor).isActive = true
The other option is to set number of lines to zero as mentioned already
noScanLabel.numberLines = 0

Answer 3

You can take UIView and add your all UILabel and arrow Image on UIView and then assign that UIView to backgroundView of TableView.
Like this.
override func numberOfSections(in tableView: UITableView) -> Int {
// if there are scans to display...
if items.count > 0 {
tableView.backgroundView = nil
tableView.separatorStyle = .singleLine
return 1
}
else { // otherwise, return 0, remove cell lines, and display a Label
let rect = CGRect(x: 0,
y: 0,
width: tableView.bounds.size.width,
height: tableView.bounds.size.height)
let messageBaseView = UIView(frame: rect)
//Add your first label..
let noScanLabel: UILabel = UILabel()
noScanLabel.text = "No Scans"
noScanLabel.textColor = UIColor.gray
noScanLabel.font = UIFont.boldSystemFont(ofSize: 24)
noScanLabel.textAlignment = NSTextAlignment.center
messageBaseView.addSubView(noScanLabel)
//Add your second label.. and your arrow image here on messageBaseView
//Assign messageBaseView to backgroundView of tableView
tableView.backgroundView = messageBaseView
tableView.separatorStyle = .none
return 0
}
}