gistfile1.m

NSMutableArray *array = [@[@1,@2,@3,@4,@5, @6, @7, @8,@9, @10] mutableCopy];

for (int i =0 ; i< [array count]; ++i) {
    if ([array[i] integerValue]> 3 && [array[i] integerValue]< 8) {
        [array removeObjectAtIndex:i];
    }
}

// we want to get an array containg [@1, @2, @3, @8, @9, @10]
// but we get                       [@1, @2, @3, @5, @7, @8, @9, @10]

gistfile2.m

// reversed: working but confusing for-loop signature
NSMutableArray *array = [@[@6, @1,@2,@3,@4,@5, @6, @7, @8,@9, @10] mutableCopy];
for (NSUInteger i = [array count] -1 ; i != NSUIntegerMax; --i) {
    if ([array[i] integerValue]> 3 && [array[i] integerValue]< 8) {
        [array removeObjectAtIndex:i];
    }
}