set up UITouch's moving range - ios

Question

I create a touch moving event for a label which size is (30, 50). here is the code
- (void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event {
UITouch *touch = [touches anyObject];
UIView *superView = self.superview;
}
But I need to make sure the label can only move inside the superview. In other word, UILabel will stop moving when it “touch” the edge of view, How to setup label's moving range?

Answer 1

Set the label to your touch position
Check whether the label's frame is inside of the superView
If it is outside,change the frame,and set userInteractionEnabled to NO
- (void)touchesMoved:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event
{
self.center = [touches.anyObject locationInView:self.superview];
CGRect bounds = self.superview.bounds;
CGRect newFrame = self.frame;
if (newFrame.origin.x < 0) {
newFrame.origin.x = 0;
self.userInteractionEnabled = NO;
}
if (newFrame.origin.y<0) {
newFrame.origin.y = 0;
self.userInteractionEnabled = NO;
}
if (newFrame.origin.x + newFrame.size.width > bounds.size.width) {
newFrame.origin.x = bounds.size.width - newFrame.size.width;
self.userInteractionEnabled = NO;
}
if (newFrame.origin.y + newFrame.size.height > bounds.size.height) {
newFrame.origin.y = bounds.size.height - newFrame.size.height;
self.userInteractionEnabled = NO;
}
self.frame = newFrame;
}