I have a method which returns a bool
value, with several exit points.
However, it does not seem to work correctly, so I would like to set an automatic breakpoint to see when it returns a YES value, so I can check all the variables and calculations in the debugger.
I would like to stop the debugger whenever a YES
value is returned.
I have a similar smart breakpoint set for objc_exception_throw
, so I know it's possible, I am just not sure how.
(In case it helps anyone, the way you can set the exception breakpoint: in the Breakpoints window (Run -> Show -> Breakpoints) enter objc_exception_throw
as "Breakpoint", and libobjc.A.dylib
as "Location")
EDIT: the specific code I would like to use it for:
- (BOOL)collisionOccured {
// Assumption: helicopter is of square shape (collision calculated by radius), walls are rectangles
// This approach is based on the solution seen here: http://stackoverflow.com/questions/401847/circle-rectangle-collision-detection-intersection/402010#402010
float helicopterImageWidth = [helicopter texture].contentSize.width;
float wallImageWidth = [[walls lastObject] texture].contentSize.width;
float wallImageHeight = [[walls lastObject] texture].contentSize.height;
float helicopterCollisionRadius = helicopterImageWidth * 0.4f;
CGPoint helicopterPosition = helicopter.position;
int numWalls = [walls count];
for (int i = 0; i < numWalls; i++) {
CCSprite *wall = [walls objectAtIndex:i];
if ([wall numberOfRunningActions] == 0) {
// The wall is not moving, we can skip checking it.
continue;
}
CGPoint wallPosition = wall.position;
float helicopterDistanceX = abs(helicopterPosition.x - wallPosition.x - wallImageWidth/2);
float helicopterDistanceY = abs(helicopterPosition.y - wallPosition.y - wallImageHeight/2);
if (helicopterDistanceX > (wallImageWidth/2 + helicopterCollisionRadius)) { return NO; }
if (helicopterDistanceY > (wallImageHeight/2 + helicopterCollisionRadius)) { return NO; }
if (helicopterDistanceX <= (wallImageWidth/2)) { return YES; }
if (helicopterDistanceY <= (wallImageHeight/2)) { return YES; }
float cornerDistance_sq = powf((helicopterDistanceX - wallImageWidth/2), 2) +
powf((helicopterDistanceY - wallImageHeight/2), 2);
return (cornerDistance_sq <= powf(helicopterCollisionRadius, 2));
}
// this should not occur
return NO;
}
This method is called via
- (void)update:(ccTime)delta {
if ([self collisionOccured]) {
NSLog(@"A collision occured");
}
}
The problem is that the update method takes delta
(time passed) as argument, so I can't check what's happening frame by frame -- whenever I continue the execution, I am presented with a different scene.
(I am using cocos2d in the code)
You can set conditional breakpoints. With a slight tweak to update:
- (void)update:(ccTime)delta {
BOOL collided = [self collisionOccured];
if (collided) {
NSLog(@"A collision occured");
}
}
you can set a breakpoint as normal after the BOOL
's assignment (i.e. on the if
line), then right-click on the blue breakpoint arrow and select "Show Message Bubble", and add collided
as the Condition. The extra variable should get optimized away in Release build mode.