for(int x=0;x<3;x++){
CGRect rect = CGRectMake(0,20 * x,100,20);
UIButton *button = [[UIButton alloc] initWithFrame:rect];
[btnframe addSubview:button];
.....
}

for(int x=0;x<5;x++){
    for(int y=0;y<5;y++){
        UIButton *button = [[UIButton alloc] initWithFrame:CGRectMake(x * 100, y * 20, 100, 20)];
        [button setText:[NSString stringWithFormat:@"%d,%d",x,y]];
        [button addTarget:self action:@selector(changeView:) forControlEvents:UIControlEventTouchUpInside];
        [mainView addSubview:button];
    }
}