How to use of NSSet
1. NSSet define NSSet *setSharp; 2. Set config setSharp = [ NSSet setWithObjects :[ NSNumber numberWithInt : 2 ], [ NSNumber numberWithInt : 4 ], [ NSNumber numberWithInt : 7 ], [ NSNumber numberWithInt : 9 ], [ NSNumber numberWithInt : 11 ], [ NSNumber numberWithInt : 14 ], [ NSNumber numberWithInt : 16 ], [ NSNumber numberWithInt : 19 ], [ NSNumber numberWithInt : 21 ], [ NSNumber numberWithInt : 23 ], nil ]; 3. set use if ([ setSharp containsObject :[ NSNumber numberWithInt :iclavier]]) { imgView. image = touchSharp ; } very fast hash calculate