Swift how to sort array of custom objects by property value

lets say we have a custom class named imageFile and this class contains two properties.

class imageFile  {
    var fileName = String()
    var fileID = Int()
}

lots of them stored in Array

var images : Array = []

var aImage = imageFile()
aImage.fileName = "image1.png"
aImage.fileID = 101
images.append(aImage)

aImage = imageFile()
aImage.fileName = "image1.png"
aImage.fileID = 202
images.append(aImage)

question is: how can i sort images array by 'fileID' ASC or DESC?

Solution 1:

First, declare your Array as a typed array so that you can call methods when you iterate:

var images : [imageFile] = []

Then you can simply do:

Swift 2

images.sorted({ $0.fileID > $1.fileID })

Swift 3+

images.sorted(by: { $0.fileID > $1.fileID })

The example above gives desc sort order

Solution 2:

[Updated for Swift 3 with sort(by:)] This, exploiting a trailing closure:

images.sorted { $0.fileID < $1.fileID }

where you use < or > depending on ASC or DESC, respectively. If you want to modify the images array, then use the following:

images.sort { $0.fileID < $1.fileID }

If you are going to do this repeatedly and prefer to define a function, one way is:

func sorterForFileIDASC(this:imageFile, that:imageFile) -> Bool {
  return this.fileID < that.fileID
}

and then use as:

images.sort(by: sorterForFileIDASC)

Solution 3:

Swift 3

people = people.sorted(by: { $0.email > $1.email })