iPad Size and Coordinates scale to iPhone - ios

Question

I'm working on this objective c game app where the screen is populated with pictures of animals.
The problem is that the size and x/y of the animal is hard coded in the app and works with the iPad Air screen dimensions. My question is how can I scale it to show up in the same position and size on an iPhone 7 plus? Is there a formula to scale the size and x/y coordinates?
I looked for answers on stackoverflow with an answer saying to divide the dimensions but when i tried that the x/y coordinates were off.
Here is the code
-(void)viewDidLoad{
[super viewDidLoad];
NSString *sonidoPathBell1 = [[NSBundle mainBundle] pathForResource:#"bellTransition" ofType:#"aif"];
NSURL *sonidoUrlBell1 = [[NSURL alloc] initFileURLWithPath:sonidoPathBell1];
AudioServicesCreateSystemSoundID((CFURLRef)sonidoUrlBell1, &sonTrans);
btnAnimales = [[NSMutableArray alloc] initWithCapacity:0];
for(int i = 0; i < 20; i++){
OBShapedButton *tempbtn = [[OBShapedButton alloc] init];
[tempbtn setTag:i+1];
opcion = [[NSUserDefaults standardUserDefaults] integerForKey:[NSString stringWithFormat:#"bluebaymobAmazingMixAndMatchObjeto%i",i + 1]];
if (opcion == 0) {
[tempbtn setImage:[UIImage imageNamed:[NSString stringWithFormat:#"btnAni%i.png",i+1]] forState:UIControlStateNormal];
}else{
[tempbtn setImage:[UIImage imageNamed:[NSString stringWithFormat:#"btnAni%iColor.png",i+1]] forState:UIControlStateNormal];
}
[tempbtn addTarget:self action:#selector(startPuzzle:) forControlEvents:UIControlEventTouchUpInside];
CGRect cuadro = CGRectMake(0, 0, 0, 0);
switch(i+1){
case 1:
cuadro = CGRectMake(131, 85, 95, 120);
//cuadro = CGRectMake(94, 48, 65, 60);
//37, 37, 30, 60
break;
case 2:
cuadro = CGRectMake(52, 246, 147, 157);
//cuadro = CGRectMake(15, 209, 117, 97);
break;
case 3:
cuadro = CGRectMake(-5, 418, 166, 158);
break;
case 4:
cuadro = CGRectMake(301, 64, 156, 151);
break;
case 5:
cuadro = CGRectMake(214, 213, 129, 190);
break;
case 6:
cuadro = CGRectMake(165, 384, 162, 169);
break;
case 7:
cuadro = CGRectMake(204, 615, 139, 153);
break;
case 8:
cuadro = CGRectMake(458, 115, 109, 90);
break;
case 9:
cuadro = CGRectMake(367, 222, 207, 130);
break;
case 10:
cuadro = CGRectMake(361, 344, 408, 276);
break;
case 11:
cuadro = CGRectMake(387, 591, 234, 173);
break;
case 12:
cuadro = CGRectMake(605, 104, 92, 131);
break;
case 13:
cuadro = CGRectMake(671, 220, 152, 155);
break;
case 14:
cuadro = CGRectMake(760, 450, 137, 174);
break;
case 15:
cuadro = CGRectMake(701, 613, 101, 161);
break;
case 16:
cuadro = CGRectMake(660, 26, 132, 88);
break;
case 17:
cuadro = CGRectMake(828, 36, 112, 107);
break;
case 18:
cuadro = CGRectMake(820, 288, 153, 157);
break;
case 19:
cuadro = CGRectMake(909, 441, 115, 162);
break;
case 20:
cuadro = CGRectMake(862, 629, 151, 135);
break;
}
//1920 x1080 iphone 7plus
//2048 x 1536 ipad
//.9375
//cuadro.origin.x = cuadro.origin.x * .9375;
//cuadro.origin.y = cuadro.origin.y * .703125;
//cuadro.origin.x = cuadro.origin.x - 37;
//cuadro.origin.y = cuadro.origin.y - 37;
//cuadro.size.width = cuadro.size.width - 30;
//cuadro.size.height = cuadro.size.height - 60;
tempbtn.frame = cuadro;
[btnAnimales addObject:tempbtn];
[self.view addSubview:[btnAnimales objectAtIndex:i]];
tempbtn = nil;
}
}