Game Development Reference
In-Depth Information
Listing 4-20. CoinsController.m (tapGesture:, partial)
- (void)tapGesture:(UIGestureRecognizer *)gestureRecognizer{
if ([coinsGame remaingTurns]>0 && acceptingInput){
UITapGestureRecognizer* tapRegognizer = (UITapGestureRecognizer*)gestureRecognizer;
CGPoint location = [tapRegognizer locationInView:coinsView];
Coord coinCoord = [self coordFromLocation:location];
if (!isFirstCoinSelected){//first of the pair
isFirstCoinSelected = true;
firstSelectedCoin = coinCoord;
[self stopCoinAt: firstSelectedCoin];
} else {
///shown in Listing 4-24
}
}
UIGestureRecognizer
that triggered this event as an argument. We will
acceptingInput
false
during animations in order to prevent the user from selecting coins midtransition,
gestureRecognizer
to
UITapGestureRecognizer
called
tapRecognizer
, we get the location of the tap by calling
and passing in
coinsView
. The location of the tap is returned as a
CGPoint
called
location
. In order to know which coin was tapped, we convert location to
Coord
by calling
coordFromLocation
, shown in Listing 4-21.
Listing 4-21. CoinsController.m (coordFromLocation:)
-(Coord)coordFromLocation:(CGPoint) location{
CGRect coinsFrame = [coinsView frame];
Coord result;
result.col = location.x / coinsFrame.size.width * [coinsGame colCount];
result.row = location.y / coinsFrame.size.height * [coinsGame rowCount];
return result;
}
The task
coordFromLocation:
takes a
CGpoint
and converts it into a
Coord
that will tell us which coin
the user tapped. To find the coin, the
x
value of the
location
is divided by the
width
of the
coinsView
and then multiplied by the number of columns. The
row
is calculated in a similar way.
In Listing 4-20, after we determine which coin was tapped and store the result as the variable
coinCoord
, we check whether the coin was previously selected. If not, we set
isFirstCoinSelected
to
true
, record which coin was selected, and call
stopCoinAt:
, shown in Listing 4-22.
