2

I want to create a button at random position in certain view. I searched and read some SO topics however I couldn't find the solution for my problem.

Here is my code:

UIButton *button1 = [UIButton buttonWithType:UIButtonTypeCustom];
CGRect buttonRect = button1.frame;
buttonRect.size = CGSizeMake(100, 100);
button1.frame = buttonRect;

[self.arr addObject:button1];

int r = ([button1 frame].size.width)/2;

int x = r + (arc4random() % (self.view.frame.size.width - button1.frame.size.width));
int y = r + (arc4random() % (self.view.frame.size.height - button1.frame.size.height));
//ERROR:Invalid operands to binary expression ('float' and 'float')

[button1 setCenter:CGPointMake(x, y)];
Amar
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THO
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  • possible duplicate of [How to make a modulo operation in objective-c / cocoa touch?](http://stackoverflow.com/questions/1271102/how-to-make-a-modulo-operation-in-objective-c-cocoa-touch) – kovpas Aug 22 '13 at 12:48
  • `width` is `CGfloat` so you are getting error. – Exploring Aug 22 '13 at 12:49

2 Answers2

9

mod (%) doesn't work on floats.

int x = r + (arc4random() % (int)(self.view.frame.size.width - button1.frame.size.width));
int y = r + (arc4random() % (int)(self.view.frame.size.height - button1.frame.size.height));

As an additional note, arc4random() % … is not recommended.

Here is the preferred method:

int x = r + arc4random_uniform(self.view.frame.size.width - button1.frame.size.width);
int y = r + arc4random_uniform(self.view.frame.size.height - button1.frame.size.height);
Jeffery Thomas
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3

try changing 

int x = r + (arc4random() % (self.view.frame.size.width - button1.frame.size.width));
int y = r + (arc4random() % (self.view.frame.size.height - button1.frame.size.height));

to

int x = r + (arc4random() % ((int)(self.view.frame.size.width - button1.frame.size.width)));
int y = r + (arc4random() % ((int)(self.view.frame.size.height - button1.frame.size.height)));

It probably throws that error because you are trying to calculate modulus using a float as parameter

Daniel
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