Segmented Control and its superview exist

Question

How to protect this method by checking to see if the segmentedControl and its superview exist before setting the frame?

- (void)setSegmentedControlFrame {
    self.segmentedControl.frame = CGRectMake(CGRectGetMinX(self.segmentedControl.superview.frame), CGRectGetMinY(self.segmentedControl.superview.frame), CGRectGetWidth(self.segmentedControl.superview.frame), CGRectGetHeight(self.segmentedControl.superview.frame));
}

score 0 · Answer 1 · answered Nov 11 '15 at 10:22

0

Do like this

- (void)setSegmentedControlFrame {
   if self.segmentedControl.isDescendantOfView(self.view)
   {
      self.segmentedControl.frame = CGRectMake(CGRectGetMinX(self.segmentedControl.superview.frame), CGRectGetMinY(self.segmentedControl.superview.frame), CGRectGetWidth(self.segmentedControl.superview.frame), CGRectGetHeight(self.segmentedControl.superview.frame));
   }

}

answered Nov 11 '15 at 10:22

Irfan Gul

1,579
13
23

That would work in objective-c but does not check explicitely self.segmentedControl for being null or not. It works because sending any method to null returns null or 0 or false respectively. So the assignment will not be executed when self.segementedControl is null. However, I doubt this is considered clean code. – Hermann Klecker Nov 11 '15 at 10:25
exactly, this is cleaner and nice. – Irfan Gul Nov 11 '15 at 10:28

score 0 · Answer 2 · answered Nov 11 '15 at 10:22

if ((self.segmentedControl) && (self.segmentedControl.superview)) {
   // do something smart here. 
}

The inner brackets are not really required. To be more specific:

if ((self.segmentedControl != null) && (self.segmentedControl.superview != null)) {
   // do something smart here. 
}

When the first condidtion of a && is checked and evaluates to false then the second is not exceuted any more. In other langauges, where accessing null objects is more of a problem, this sequence is important.

Is this what you have asked for?

Segmented Control and its superview exist

2 Answers2