iOS Question MAPs > for each but backwarts like step -1

sorex · Feb 29, 2016

Hello,

Is there a way to iterate backwarths over map items?

In B4A I can use a for loop with step -1 combined with .getvalueat and/or .getkeyat but B4i doesn't have these methods.

I want to remove items without getting errors that I'm trying to read none existing map entries due to none updated map limit counters.

Erel · Mar 1, 2016

sorex said:
In B4A I can use a for loop with step -1 combined with .getvalueat and/or .getkeyat but B4i doesn't have these methods.

You shouldn't use GetValueAt / GetKeyAt anymore. Especially not by stepping backwards. It will be very inefficient.

Correct solution that will work on all platforms:

B4X:

Dim m As Map = CreateMap("a": 1, "b": 2, "c": 1)

Dim keysToRemove As List
keysToRemove.Initialize
For Each k As String In m.Keys
   If m.Get(k) = 1 Then keysToRemove.Add(k) 'remove all items with value = 1.
Next
For Each k As String In keysToRemove
   m.Remove(k)
Next

sorex · Mar 1, 2016

thanks, I thought it would've been be something like that.

iOS Question MAPs > for each but backwarts like step -1

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Erel

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