Certain placement of UIButtons created in for loop - ios

Question

I want to create UIButtons and have them separated inside a UIScrollView with pages such as:
The buttons will go from left to right then down in rows until it gets to bottom of view. It will then go to next page of the UIScrollView and continue on.
Here's my code so far:
for(NSString *num in nums) {
UIButton *test = [UIButton buttonWithType:UIButtonTypeRoundedRect];
[test addTarget:self action:#selector(numPressed:) forControlEvents:UIControlEventTouchUpInside];
test.frame = CGRectMake(0, 0, 70, 70);
[self.view addSubview:test];
}

Answer 1

Some code like this:
int xOff = 10;
int yOff = 50;
int btnGap = 20;
int page = 0;
for (NSString *num in nums) {
xOff += page * _scrollView.width;
for (int row = 0; row < 3; row++) {
for (int col = 0; col < 3; col++) {
UIButton *test = [UIButton buttonWithType:UIButtonTypeRoundedRect];
[test addTarget:self action:#selector(numPressed:) forControlEvents:UIControlEventTouchUpInside];
test.frame = CGRectMake(xOff+col*(70+btnGap) , yOff+row*(70+btnGap), 70, 70);
test.backgroundColor = [UIColor redColor];
[test setTitle:num forState:UIControlStateNormal];
[_scrollView addSubview:test];
}
}
page++;
}

Answer 2

You need to change the coordinates when invokint CGRectMake:
NSInteger i, x, y;
for(NSString *num in nums) {
...
i = i%3;
if (i==0)
{
x = 0;
y += 70;
}
x += 80;
test.frame = CGRectMake(x, y, 70, 70);
...
}
This should give you an idea on how to proceed. Also, don't forget to place the title to each button.

Answer 3

If you're creating and setting UIButton objects by frame then I, personally, would do it this way (surely it can be improved / optimized)
Note: This does not incorporate any page logic so you'll need to adapt it yourself.
-(void)createButtonGrid
{
int i_btnWidth = 70;
int i_btnHeight = 70;
int i_btnX = 0;
int i_btnY = -70; //offset (for first iteration in for loop) [1]
int i_btnPadding = 20;
//number of columns
int i_screenDivisions = 3;
//width of every column
int i_screenDivisionWidth = self.view.frame.size.width / i_screenDivisions;
int i_count = 40; //or, maybe, nums.count as per your logic
for (int i = 0; i < i_count; i++) {
//which column a button goes in
int i_index = (i+i_screenDivisions)%i_screenDivisions;
//increase Y position when new row begins
if (i_index == 0) { //[1]
i_btnY += i_btnHeight + i_btnPadding;
}
//calculate X position (which will be placed at the centre of every column)
i_btnX = (i_index*i_screenDivisionWidth) + (i_screenDivisionWidth/2) - (i_btnWidth/2);
//----Button creation logic----
UIButton *btnTemp = [UIButton buttonWithType:UIButtonTypeCustom];
[btnTemp setFrame:CGRectMake(i_btnX, i_btnY, i_btnWidth, i_btnHeight)];
NSString *strTitle = [NSString stringWithFormat:#"%d",i];
//or, maybe, as per your logic
//NSString *strTitle = nums[i];
[btnTemp setTitle:strTitle forState:UIControlStateNormal];
[btnTemp.titleLabel setTextColor:[UIColor yellowColor]];
//[btnTemp addTarget:self action:nil forControlEvents:UIControlEventTouchUpInside];
[btnTemp setTag:i]; //might need it later
[btnTemp setBackgroundColor:[UIColor colorWithRed:(float)(arc4random()%255)/255
green:(float)(arc4random()%255)/255
blue:(float)(arc4random()%255)/255
alpha:1.0f]];
[scrollView addSubview:btnTemp];
}
[scrollView setContentSize:CGSizeMake(self.view.frame.size.width, i_btnY + i_btnHeight)];
}