Swift: sort array by multiple criteria (weights) [duplicate]

Question

I've already read similar questions/answer, but none of it resolve my problem.

I've an object like this

class Chat {
    unreadMessages: Int = 0
    messages: Int = 0
}

Then I have an array of Chat objects, and I need to order it by multiple criteria, first by chat with grater unread messages and then chat with grater total messages.

Es.

  Obj  TotMes Unread  
  Chat A 10 3   
  Chat B  1 0     
  Chat C  4 0   
  Chat D  9 9

Desidered output:

Chat D  9 9   
Chat A 10 3   
Chat C  4 0  
Chat B  1 0

I try with this sort alhoritm, but don't seems work:

let sorted = chats.sort({ (c1, c2) -> Bool in   
   if c1.unreadMessages > c2.unreadMessages {
      return true
   }
   if c1.messages > c2.messages {
      return true
   }        
   return false
})

Can someone explain me what is wrong with this?

Think about it: What should happen if c1.unreadMessages < c2.unreadMessages ? — Martin R
– Martin R, Commented Nov 24, 2015 at 9:01

Greg · Accepted Answer · 2015-11-24 09:02:06Z

5

You haven't got condition for c1.unreadMessages < c2.unreadMessages that should cover all requirements:

let sorted = chats.sort({ (c1, c2) -> Bool in   
   if c1.unreadMessages > c2.unreadMessages {
      return true
   } else if c1.unreadMessages < c2.unreadMessages {
      return false
   } else if c1.messages > c2.messages {
      return true
   }        
   return false
})

answered Nov 24, 2015 at 9:02

Greg

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1 Comment

Luca Davanzo Over a year ago

Damn! Sure I forget one condition.. my fault! Thanks man!

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