iOS pan recogniser added through interface builder - iphone

Question

I say first that I'm completely new to objectiveC and am also working with interface builder the first time.
I just want to make the pan gesture work (I will need the zoom gesture also for what I really want to do but I thought if I start with the easier pan).
I followed some tutorial but it still doesn't work neither on my iPhone 5 nor in the simulator.
I've started the thing based on a page based application. I then established a new view and a view controller for that one. Then I dragged and dropped the Pan Gesture from Interface builder to the view. User Interaction on the view is enabled.
Here is my code:
uACropViewController.h
#import <UIKit/UIKit.h>
#interface uACropViewController : UIViewController
- (IBAction)handlePan:(UIPanGestureRecognizer *)recognizer;
#property (weak, nonatomic) IBOutlet UIImageView *CropImage;
#property (strong, nonatomic) IBOutlet UIPanGestureRecognizer *onGestureAction;
#end
uACropViewController.m
#import "uACropViewController.h"
#interface uACropViewController ()
#end
#implementation uACropViewController
#synthesize CropImage;
static CGPoint originalPoint;
- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
if (self) {
// Custom initialization
}
return self;
}
- (void)viewDidLoad
{
[super viewDidLoad];
// Do any additional setup after loading the view.
//for resetting the center of the image, when the pan gesture is ended.
originalPoint=CropImage.center;
}
- (void)didReceiveMemoryWarning
{
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}
-(IBAction)onGestureAction:(id)sender{
if ([sender isKindOfClass:[UIPanGestureRecognizer class]]) {
//is a pan gesture
UIPanGestureRecognizer *recognizer=(UIPanGestureRecognizer *)sender;
if (recognizer.state==UIGestureRecognizerStateBegan||recognizer.state==UIGestureRecognizerStateChanged) {
CGPoint nextPoint= [recognizer translationInView:self.view];
CGPoint currentPoint=CropImage.center;
currentPoint.x +=nextPoint.x;
currentPoint.y +=nextPoint.y;
CropImage.center=currentPoint;
[recognizer setTranslation:CGPointZero inView:self.view];
}
if (recognizer.state==UIGestureRecognizerStateEnded) {
CropImage.center=originalPoint;
[recognizer setTranslation:CGPointZero inView:self.view];
}
return;
}
}
#end
To be honest I have no idea of what's going wrong here. so any help or pointers are appreciated!
thanks,
Suse

Answer 1

The IBOutlet is the reference to that object in the view, the IBAction is the action that is called when an event is triggered on that variable.
For example, you can have a UIButton IBOutlet to change properties of the UIButton like the size, and a UIButton IBAction to recognise when the button is pressed.
In your case, onGestureAction is a variable that points to that gesture recognizer, and hanldePan: is the action responder.
Try adding the method here:
- (IBAction)handlePan:(UIPanGestureRecognizer *)recognizer
{
if (recognizer.state==UIGestureRecognizerStateBegan||recognizer.state==UIGestureRecognizerStateChanged) {
CGPoint nextPoint= [recognizer translationInView:self.view];
CGPoint currentPoint=CropImage.center;
currentPoint.x +=nextPoint.x;
currentPoint.y +=nextPoint.y;
CropImage.center=currentPoint;
[recognizer setTranslation:CGPointZero inView:self.view];
}
if (recognizer.state==UIGestureRecognizerStateEnded) {
CropImage.center=originalPoint;
[recognizer setTranslation:CGPointZero inView:self.view];
}
return;
}