How to initialize a programmatic UITableViewCell with a property via dependency injection? - ios

Question

I've looked around and I can't find any examples of this. I simply want to create a custom initializer on a programmatic UITableViewCell subclass that includes one property.
class CustomCell: UITableViewCell {
var foo: Foo
required init(coder aDecoder: NSCoder) {
fatalError("init(coder:) has not been implemented")
}
// custom init with a foo
}
What I want is:
let cell = CustomCell(foo: myFoo) // other default init params if needed
Not:
let cell = CustomCell()
cell.foo = myFoo
Pointing me to a resource (if I missed one) that shows an implementation like this would be great. I assume this is a common need, but a couple hours being yelled at by init compiler errors and a few Medium articles later and I can't find anything.

Answer 1

Instances of UITableViewCell are created by the system, using the classic init(style: UITableViewCell.CellStyle, reuseIdentifier: String?) initializer.
Don't forget to add this magic line after initializing your UITableView:
myTableView.register(CustomCell.self, forCellReuseIdentifier: Constant.myCellReuseIdentifier)
Let's say you write this:
class CustomCell: UITableViewCell {
convenience init(reuseIdentifier: String, customObject: Any?) {
self.init(style: UITableViewCell.CellStyle.default, reuseIdentifier: reuseIdentifier)
}
override init(style: UITableViewCell.CellStyle, reuseIdentifier: String?) {
super.init(style: style, reuseIdentifier: reuseIdentifier)
}
required init?(coder: NSCoder) {
fatalError("init(coder:) has not been implemented")
}
}
Then you can create a cell with this line of code:
let cell = CustomCell(reuseIdentifier: Constant.myReuseIdentifier, customObject: nil)
... but what will you do with this cell? How to plug it into your "tableview's cells management" logic.
To inject something to your cell, you may plug in:
tableView(_:cellForRowAt:) for a UITableView (in the object implementing UITableViewDataSource)
collectionView(_:cellForItemAt:) or collectionView:willDisplayCell:forItemAtIndexPath: for a UICollectionView.
Those 3 methods may be call very frequently by the system, avoid memory allocations or any memory / CPU intensive task when possible.