Building drag and drop interface on iphone

问题

I am trying to build an app which will have a bunch of cards that the user needs to drag and drop them onto specific drop zones. How would one go about detecting this and if the card is not on the drop zone then it should slide back.

Any suggestions on how to structure this app?

回答1:

View.center test against your boundary bounds. something like this maybe:

if(((draggedBox.center.x >= droppingBox.origin.x) && 
             (draggedBox.center.y <= droppingBox.origin.y)) && 
             (draggedBox.center.x <= (droppingBox.origin.x + droppingBox.width) && 
             (draggedBox.center.y >= (droppingBox.origin.y + droppingBox.height))) {

   //do stuff because its inside
} 

else {

   //send it back from whence it came
   draggedBox.center = cgpointmake(originalXposition,originalYposition);

}

回答2:

You should look at CGRectContainsRect(draggedBox.frame, droppingBox.frame);

来源：https://stackoverflow.com/questions/2955629/building-drag-and-drop-interface-on-iphone