How to sort an array by boolean filed in swift?

Question

I have a class defined like this:

class someClass {
   var isCompleted = false
}

how to sort the list of the someClass? if want to move the completed items to the top of the list.

How big is the list? I think two .filters or even a loop will likely be clearer to reaso about (and likely faster but who cares) — Benjamin Gruenbaum
– Benjamin Gruenbaum, Commented Mar 4, 2015 at 6:18
@BenjaminGruenbaum You mean filter it and combine the result? — backslash112
– backslash112, Commented Mar 4, 2015 at 6:21
Yes, you can also directly sort it but a sort on a boolean is just weird — Benjamin Gruenbaum
– Benjamin Gruenbaum, Commented Mar 4, 2015 at 6:22
@A-Live Filter it and combine the result, but maybe there are some better ways. — backslash112
– backslash112, Commented Mar 4, 2015 at 6:25

Martin R · Accepted Answer · 2015-03-04 07:06:53Z

7

You can sort according to the boolean property by converting the values to Int:

let arrayOfClasses =  ... // array of classes

let sortedArrayOfClasses = sorted(arrayOfClasses) {
    Int($0.isCompleted) > Int($1.isCompleted)
}

Or with "in-situ" sort:

var arrayOfClasses =  ... // array of classes

sort(&arrayOfClasses) {
    Int($0.isCompleted) > Int($1.isCompleted)
}

answered Mar 4, 2015 at 7:06

Martin R

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Comments

rintaro · Accepted Answer · 2015-03-04 08:19:38Z

3

parameter closure for sort or sorted returns true iff the first parameter must be ordered before the second, otherwise false.

So you can:

let array = [ ... ]

let sortedArray = array.sorted { a, b in
    a.isCompleted && !b.isCompleted
}

answered Mar 4, 2015 at 8:19

rintaro

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1 Comment

dchakarov Over a year ago

Works great, thank you! I shortened it to array.sorted { $0.isCompleted && !$1.isCompleted }

Dejan Skledar · Accepted Answer · 2015-03-04 06:22:54Z

0

var yourArrayOfBooleans:[SomeClass] = ...

var sortedArrayOfBooleans:[SomeClass] = []
var tmpArray:[SomeClass] = []

for ar in yourArrayOfBooleans
{
     if ar.isCompleted
     {
          sortedArrayOfBooleans.append(ar)
     }
     else
     {
         tmpArray.append(ar)
     }
}
sortedArrayOfBooleans += tmpArray

answered Mar 4, 2015 at 6:22

Dejan Skledar

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