How do I apply a UILongPressGestureRecognizer to a shape in C4? - ios5

Question

I am working in C4 and want to be able to press down on a shape and drag it at a slow speed upward.
I have been working with the "Getting the UITouch objects for a UIGestureRecognizer" tutorial and other TouchesMoved and TouchesBegan Objective-C tutorials but the gesture is not applying to the shape. The project builds but the shape still does not move when you press and drag it. Is there a particular way C4 applies gestures to shapes?
This is my code:
DragGestureRecognizer.h
#import <UIKit/UIKit.h>
#interface DragGestureRecognizer : UILongPressGestureRecognizer {
}
- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event;
#end
#protocol DragGestureRecognizerDelegate <UIGestureRecognizerDelegate>
- (void) gestureRecognizer:(UIGestureRecognizer *)gr movedWithTouches:(NSSet*)touches andEvent:(UIEvent *)event;
#end
C4WorkSpace.m:
#import "C4WorkSpace.h"
#import "DragGestureRecognizer.h"
#implementation DragGestureRecognizer
- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event {
[super touchesMoved:touches withEvent:event];
if ([self.delegate respondsToSelector:#selector(gestureRecognizer:movedWithTouches:andEvent:)]) {
[(id)self.delegate gestureRecognizer:self movedWithTouches:touches andEvent:event];
}
}
#end
#implementation C4WorkSpace {
C4Shape *circle;
}
- (void)longPress:(UILongPressGestureRecognizer*)gesture {
if ( gesture.state == UIGestureRecognizerStateEnded ) {
NSLog(#"Long Press");
}
}
-(void)setup {
circle = [C4Shape ellipse:CGRectMake(5,412,75,75)];
[self.canvas addShape:circle];
}
#end

Answer 1

C4 has a method that simplifies the process of adding gestures to any visible object (e.g. C4Shape, C4Movie, C4Label...).
NOTE: you will need to create a subclass of C4Shape in which you can create some custom methods.
For instance, the following will add a tap gesture to an C4Shape:
C4Shape *s = [C4Shape rect:CGRectMake(..)];
[s addGesture:TAP name:#"singleTapGesture" action:#"tap"];
The addGesture:name:action: method is listed in the C4Control documentation, and is defined like:
Adds a gesture to an object.
- (void)addGesture:(C4GestureType)type name:(NSString *)gestureName action:(NSString *)methodName
The (C4GestureType)type can be any one of:
TAP
SWIPERIGHT
SWIPELEFT
SWIPEUP
SWIPEDOWN
PAN
LONGPRESS
The following gestures are available, but haven't yet been tested:
PINCH
ROTATION
The (NSString *)gestureName allows you to specify a unique name for the gesture.
The (NSString *)methodName allows you to specify the method that the gesture will trigger.
So... getting back to the example above:
[s addGesture:TAP name:#"singleTapGesture" action:#"tap"];
...will add to the s object a TAP gesture called singleTapGesture which, when triggered, will run a -(void)tap; method (which needs to have already defined in your class).
You can apply the technique I described above, but instead use:
[s addGesture:PAN name:#"panGesture" action:#"move:];
you will also have to define a
-(void)move:(id)sender;
method in your shape's class.