Initialise your array before of while loop
FMResultSet *results = nil;
results=[database executeQuery:@"SELECT * FROM CLINIQDB"];
countryArr=[[NSMutableArray alloc] init];
while([results next])
{
[countryArr addObject:[results stringForColumn:@"countryNames"]];
}
NSLog(@"The country arr %@",countryArr);
[database close];