(iOS) Drag and drop, Snap to grid, Check proper area - ios

Question

I've read all the stuff about drag'n'drop and gestureRecognizer but haven't found the solution.
I got "gamefield" 10x10 and I want to implement drag'n'drop with snap to grid and check if element placed on "gamefield".
I got my 8 "TempButtons" added to UIView buttonsSuperView with action:#selector(imageMoved:withEvent:).
- (IBAction) imageMoved:(id) sender withEvent:(UIEvent *) event
{
UIControl *control = sender;
originalPosition = [self getButton:sender];
UITouch *touch = [[event allTouches] anyObject];
point = [touch locationInView:control];
float step = 31.0; // Grid step size.
CGPoint center = control.center;
center.x += step * floor((point.x / step));
center.y += step * floor((point.y / step));
control.center = center;
}
It works, I can move any button with grid step 31px. I can place it everywhere, but I have to put it on UIView fieldView. If it placed right there it's OK and I can replace it on another tile. But if I place it outside fieldView the button should return on its place. Something like this:
if ([self.fieldView pointInside:point withEvent:nil])
{
control.center = center;
} else {
[UIView animateWithDuration:0.4
delay:0.0
options:UIViewAnimationOptionCurveEaseInOut
animations:^ {
control.center = originalPosition;
// to
}
completion:^(BOOL finished) {}];
}
If this code placed on - (IBAction) imageMoved:(id) sender withEvent:(UIEvent *) event method it makes button get back to its "originalposition" all the time its moving. But I need to check if its placed properly only on 'touchesEnded'. But that's another method and I don't understand how to realize which button pressed and its original coords to get back if placed improperly.
Maybe there's a better way to use 'UIView' instead of 'UIButton' but I still don't understand how to do that.
Thanks in advance.
Kind Regards,
Nick

Answer 1

Since no one answered my question I've spent some time and found working solution.
- (IBAction) imageMoved:(id) sender withEvent:(UIEvent *) event
{
dragObject = sender;
originalPosition = [self getButton:sender];
UITouch *touch = [[event allTouches] anyObject];
point = [touch locationInView:dragObject];
float step = 31.0; // Grid step size.
CGPoint center = dragObject.center;
center.x += step * floor((point.x / step));
center.y += step * floor((point.y / step));
dragObject.center = center;
[sender addTarget:self action:#selector(touchesEnded:withEvent:) forControlEvents:UIControlEventTouchUpInside];
}
- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event
{
if (![fieldView pointInside:dragObject.center withEvent:nil])
{
[UIView animateWithDuration:0.4
delay:0.0
options:UIViewAnimationOptionCurveEaseInOut
animations:^ {
dragObject.center = CGPointMake(originalPosition.x + 15.5, originalPosition.y + 15.5);
}
completion:^(BOOL finished) {}];
}
}
Now it works like charm and I can move along. My buttons moving freely snapped to grid and when pleced outside game field they move back to their original position.
Regards,
Nick