int main(int argc, const char * argv[]) {    //for,foreach,while,do-while,switch        NSMutableArray* mutableArray = [NSMutableArray arrayWithCapacity:2];        [mutableArray addObject:@"item1"];    [mutableArray addObject:@"item2"];    [mutableArray addObject:@"item3"];        NSLog(@"-------------------for---------------------");    for(NSUInteger i=0;i<[mutableArray count];i++)    {        NSLog(@"%@",[mutableArray objectAtIndex:i]);    }            NSLog(@"-------------------foreach---------------------");        for (id item in mutableArray) {        NSLog(@"%@",item);    }        NSLog(@"-------------------while---------------------");        NSUInteger count = 0;    while (count < [mutableArray count]) {        NSLog(@"%@",[mutableArray objectAtIndex:count]);        count++;    }        NSLog(@"-------------------do-while---------------------");    count = 0;    do{        NSLog(@"%@",[mutableArray objectAtIndex:count]);        count++;    }while (count<[mutableArray count]);        NSLog(@"-------------------switch---------------------");    int expression=4;    switch (expression) {        case 1:            NSLog(@"expression=1");            break;        case 2:            NSLog(@"expression=2");            break;        default:            NSLog(@"expression=default");            break;    }        return 0;}