iOS GestureRecognizers All Directions - ios

Question

I am fairly new to iOS development. I have just started about a month or two ago. I have an idea for an application, but it would require Gesture Recognizers. I have looked for the documentation for Gesture Recognizers but as far as I can tell, it can only detect 4 directions. Up, left, right, and down. Is there anyway to write some code that will let you detect any direction the user swipes. For example, if the user were to swipe towards the upper-right direction or bottom-right direction, is there a way to detect that?
EDIT: After thinking about this I have come up with a better way to explain what I need code for. If I was developing a game for iOS and the user is usually in a camera view (birds-eye view) and I wanted to allow them to move their view in a map so that they could perhaps view an enemy's base or their ally's base, how would I detect those diagonal swipes rather than just up, right, left, and down swipes?

Answer 1

I think you are a little confused.
UISwipeGestureRecognizer is a subclass of UIGestureRecognizer, and, as you say, it only detects swipes for those 4 directions.
But then there's UIPanGestureRecognizer which you can use to detect movement in any direction. It gives you a method called translationInView: which gives you just that, the change of the position of your finger in whichever direction.

Answer 2

I ran across your question, since it was something similar to what I wanted to do, but then ended up not using it. So I figured I'd leave the code here for posterity. Just use an UIPanGestureRecognizer and set a method similar to this one for your target/selector:
typedef enum {
NONE = 0,
LEFT = 1,
RIGHT = 2,
UP = 4,
DOWN = 8
} BLDirection;
-(void)detectDirection:(UIPanGestureRecognizer*)pan {
if (pan.state == UIGestureRecognizerStateEnded) {
CGPoint stopPan = [pan translationInView:self.view];
CGPoint velocity = [pan velocityInView:self.view];
int direction = NONE;
// first determine the directions
if (velocity.x < 0) {
direction |= LEFT;
} else if (velocity.x > 0) {
direction |= RIGHT;
}
if (velocity.y < 0) {
direction |= UP;
} else if (velocity.y > 0) {
direction |= DOWN;
}
// now we figure out the angle of the swipe
double x2 = stopPan.x;
double x1 = 0;
double y2 = abs(stopPan.y);
double y1 = 0;
// angle is in degrees
double angle = atan((y2 - y1 + 1) / (x2 - x1 + 1)) * 57.29577951308233; // 180/pi
// mask out the vertical directions if they aren't sufficiently strong
if ((angle < 0 && angle < -55) || (angle > 0 && angle > 55)) {
direction &= (UP | DOWN);
}
// mask out the horizontal directions if they aren't sufficiently strong
if ((angle < 0 && angle > -35) || (angle > 0 && angle < 35)) {
direction &= (LEFT | RIGHT);
}
NSLog(#"Direction is %s%s%s%s", ((direction & UP) == UP) ? "UP" : "",
((direction & DOWN) == DOWN) ? "DOWN" : "",
((direction & LEFT) == LEFT) ? "LEFT" : "",
((direction & RIGHT) == RIGHT) ? "RIGHT" : "");
// do something here now that you know the direction. The direction could be one of the following:
// UP
// DOWN
// LEFT
// RIGHT
// UP|LEFT
// UP|RIGHT
// DOWN|LEFT
// DOWN|RIGHT
}
}