objective c - Sorting an NSTableColumn using transformed values -


my class has property enum. property bound nstablecolumn. 

typedef enum _status {     unknown=0,     win,     osx } status;

in order make sure nstablecolumn shows proper string representation, instead of displaying numeric 0, 1, , 2, use nsvaluetransformer.

so unknown becomes "unknown os". win becomes "ms windows" , osx becomes "osx 10.8". table column displays these values correctly.

i need sort column using transformed values. if use

[nssortdescriptor sortdescriptorwithkey:@"status"                               ascending:yes                                selector:@selector(compare:)];

the column sorted in order:

unknown os
ms windows
osx 10.8

which make sense because 0 < 1 < 2. require sorted using string counterparts, make it:

ms windows
osx 10.8
unknown os

how can without changing order of enum?

you're using standard compare: method in selector. it's comparing enums. create own method compares way want. can call nsvaluetransformer string values, , compare those, , return appropriate nscomparisonresult.

[edit] ok first suggestion won't work (without using categories). should. assuming myvaluetransformer instantiated, , status nsnumber:

sortdescriptor = [nssortdescriptor sortdescriptorwithkey:@"status" ascending: yes                                                            comparator:^(id first, id second){     nsnumber* firstnum = (nsnumber*)first;     nsnumber* secondnum = (nsnumber*)second;     if ([myvaluetransformer transformedvalue:firstnum] == [myvaluetransformer transformedvalue:secondnum]) {         return nsorderedsame;     } else if ([myvaluetransformer transformedvalue:firstnum] > [myvaluetransformer transformedvalue:secondnum]) {         return nsordereddescending;     } else {         return nsorderedascending;     } }];

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