How to split indexPath array into seperate array of indexPath, each array's indexPath has same indexPath.section

Question

Recently I want to delete cells according to indexPaths, so the input parameter of the function is [IndexPath] type, I need to split the [IndexPath] to several arrays according to the indexPath.section, is there any easy way to do this? For example

indexPaths = 
[IndexPath(row: 0, section: 1),
 IndexPath(row: 1, section: 1), 
 IndexPath(row: 2, section: 1), 
 IndexPath(row: 2, section: 0)]

want to convert this to

indexPath1 = 
[IndexPath(row: 0, section: 1),
 IndexPath(row: 1, section: 1), 
 IndexPath(row: 2, section: 1)]

indexPath0 = 
[IndexPath(row: 2, section: 0)]

// maybe get a [Array]
[indexPath0, indexPath1]

Answer 1

One possible solution is to first build a dictonary where the keys are the section numbers and the values are the array of IndexPath in that section.

let indexPaths = [
    IndexPath(row: 0, section: 1),
    IndexPath(row: 1, section: 1),
    IndexPath(row: 2, section: 1),
    IndexPath(row: 2, section: 0),
]

let pathDict = Dictionary(grouping: indexPaths) { (path) in
    return path.section
}

Then you can map this dictionary into an array of the path arrays. But first sort those arrays by the section.

let sectionPaths = pathDict.sorted { (arg0, arg1) -> Bool in
    return arg0.key < arg1.key // sort by section
}.map { $0.value } // get just the arrays of IndexPath

print(sectionPaths)

Output:

[[[0, 2]], [[1, 0], [1, 1], [1, 2]]]