How to restrict uilabel to be dragged within a particular frame only? - iphone

Question

I have added one label in imageview and added Pangesture for dragging label.With this code label is dragged within the whole.but i want to restrict the label drag within the frame of uiimageview only.
How can i achieve this? The code for adding lable and gesture is as below.
lblQuote=[[UILabel alloc]init];
lblQuote.frame=CGRectMake(130,380, 400,100);
lblQuote.userInteractionEnabled=TRUE;
lblQuote.backgroundColor=[UIColor clearColor];
lblQuote.userInteractionEnabled=TRUE;
lblQuote.lineBreakMode=UILineBreakModeWordWrap;
lblQuote.font=[UIFont systemFontOfSize:40.0];
lblQuote.tag=500;
lblQuote.text=#"";
CGSize maximumLabelSize = CGSizeMake(296,9999);
CGSize expectedLabelSize = [strQuote sizeWithFont:lblQuote.font
constrainedToSize:maximumLabelSize
lineBreakMode:lblQuote.lineBreakMode];
//adjust the label the the new height.
int nooflines=expectedLabelSize.height/16.0;
lblQuote.numberOfLines=nooflines;
// CGRect newFrame = lblQuote.frame;
//newFrame.size.height = expectedLabelSize.height;
// yourLabel.frame = newFrame;
lblQuote.textAlignment=UITextAlignmentCenter;
UIPanGestureRecognizer *gesture = [[[UIPanGestureRecognizer alloc]
initWithTarget:self
action:#selector(labelDragged:)] autorelease];
[lblQuote addGestureRecognizer:gesture];
- (void)labelDragged:(UIPanGestureRecognizer *)gesture
{
UILabel *label = (UILabel *)gesture.view;
CGPoint translation = [gesture translationInView:label];
// move label
label.center = CGPointMake(label.center.x + translation.x,
label.center.y + translation.y);
// reset translation
[gesture setTranslation:CGPointZero inView:label];
}
I tried moving label on touches event.code is as below:
- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event
{
UITouch *touch = [touches anyObject];
CGPoint pointMoved = [touch locationInView:imgView2];
lblQuote.frame=CGRectMake(pointMoved.x, pointMoved.y, lblQuote.frame.size.width, lblQuote.frame.size.height);
}
But movement is not as smooth as pan gesture recognizer.sometimes touch is in another direction and label movement in some other direction and sometimes more or less movement than touch.

Answer 1

Well this is totally depends on your logics although i wrote a code for you, hope this will help you!!
Make sure your UILabel UserIntraction is set to be YES; and use touch began and touch moved methods instead of pangesture.... see this now
-(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
UITouch *touch = [[event allTouches]anyObject];
if([touch view] == lblName)
{
NSLog(#"touch on label");
CGPoint pt = [[touches anyObject] locationInView:lblName];
startLocation = pt;
// startLocation is a CGPoint declare globaly in .h..and lblName is your UILabel
}
}
- (void) touchesMoved:(NSSet *)touches withEvent: (UIEvent *)event
{
UITouch *touch = [[event allTouches]anyObject];
if([touch view] == lblName)
{
CGPoint pt = [[touches anyObject] previousLocationInView:lblName];
CGFloat dx = pt.x - startLocation.x;
CGFloat dy = pt.y - startLocation.y;
CGPoint newCenter = CGPointMake(lblName.center.x + dx, lblName.center.y + dy);
//now put if condition for dragging in specific area
CGFloat min_X = lblName.center.x + dx - lblName.frame.size.width/2.0;
CGFloat max_X = lblName.center.x + dx + lblName.frame.size.width/2.0;
CGFloat min_Y = lblName.center.y + dy - lblName.frame.size.height/2.0;
CGFloat max_Y = lblName.center.y + dy + lblName.frame.size.height/2.0;
if((min_X >= imageView.frame.origin.x && max_X <= imageView.frame.origin.x + imageView.frame.size.width) && (min_Y >= imageView.frame.origin.y && max_Y <= imageView.frame.origin.y + imageView.frame.size.height))
{
lblName.center = newCenter;
}
}
}