如何在Swift中为UITableView处理数组中的两种不同类型

Question

We are thinking of migrating an app from obj-c to Swift. One issue is that we have a UITableView in our obj-c code that has objects that are either of type Header or of type Item . Basically, it resolves which type it has at cellForRowAtIndexPath. Swift Arrays (to the best of my knowledge) can only handle a single type. Given this, how could we handle two different types to be used in a UITableView? Would a wrapper object like DataObj where we have nillable instance of each work?

Answer 1

Here is an approach that uses a protocol to unite your two classes:

protocol TableItem {

}

class Header: TableItem {
    // Header stuff
}

class Item: TableItem {
    // Item stuff
}

// Then your array can store objects that implement TableItem
let arr: [TableItem] = [Header(), Item()]

for item in arr {
    if item is Header {
        print("it is a Header")
    } else if item is Item {
        print("it is an Item")
    }
}

The advantage of this over [AnyObject] or NSMutableArray is that only the classes which implement TableItem would be allowed in your array, so you gain the extra type safety.

Answer 2

Swift arrays can store objects of different types. To do so you must declare as AnyObject array

var array:[AnyObject] = []

After this on cellForRowAtIndexPath you can get type of object using optional unwrapping

if let header = array[indexPath.row] as? Header{
    //return header cell here
}else{

    let item = array[indexPath.row] as! Item

    // return item cell

}