objective c - Sprite goes above/below the limits of grid movement system -

i'm trying implement grid movement in game. grid has 1 column , 3 lines.

[ ] y3 - 60 % of height [ ] y2 - 40% of height [ ] y1 - 20% of height 

in iphone 3.5 inch, these height are:

[ ] y3 - 193px [ ] y2 - 128px [ ] y1 - 64px 

when user taps screen above npc, npc should move next cell above him (e.g. if npc in y1, should go y2). , same thing should happen in opposite direction. but, npc should never com above 193px or below 64px. not happening. if tap twice, when npc moving, starts moving faster , ignores grind, , go above/below boundaries.

this code. how can improve want?

-(void) touchbegan:(uitouch *)touch withevent:(uievent *)event {  cgpoint touchlocation = [touch locationinnode:self];  positiony1 = self.contentsize.height*.2; positiony2 = self.contentsize.height*.40; positiony3 =  self.contentsize.height*.60;   float playermove;  if (touchlocation.y > _player.position.y) {      if (_player.position.y >= positiony3) {         nslog(@"decisao 1");         playermove = positiony3;      } else  if (_player.position.y >= positiony2 && _player.position.y <= positiony3) {         nslog(@"decisao 2");         playermove = positiony3;      } else  if (_player.position.y >= positiony1 && _player.position.y <= positiony2) {         nslog(@"decisao 3");         playermove = positiony2;      } else  if (_player.position.y <= positiony1) {         nslog(@"decisao 4");         playermove = positiony1;      }             } else if ((touchlocation.y < _player.position.y)) {      if (_player.position.y <= positiony1) {         nslog(@"decisao 5");         playermove = positiony1;      } else  if (_player.position.y >= positiony1 && _player.position.y <= positiony2) {         nslog(@"decisao 6");         playermove = positiony1;      } else  if (_player.position.y >= positiony2 && _player.position.y <= positiony3) {         nslog(@"decisao 7");         playermove = positiony2;      } else  if (_player.position.y >= positiony3) {         nslog(@"decisao 8");         playermove = positiony3;      }   }  // move our sprite touch location ccactionmoveto *actionmove = [ccactionmoveto actionwithduration:1.0f position:cgpointmake(_player.position.x, playermove)]; [_player runaction:actionmove]; 

}

one problem allow multiple move actions stop, every time tap move action runs regardless of whether there's move action running. remove move actions (or of them) before running new one:

[_player stopallactions]; // or: remove tag [_player runaction:actionmove]; 

next, if none of if/else true value of playermove left undefined:

float playermove; 

if happen variable may hold value @ random, possibly moving node far, far away screen. that'll make appear sprite disappear , give hard time figure out what's going on.

it practice, practice indeed, initialize standard value types default value:

float playermove = 0.0;