Color pixel with tap recognizer

hello need ios app. how can background color of image (that insert in uiimageview) tap. create tap gesture recognizer not know how read background color tap.

try part of code found on stackoverflow:

in viewdidload:

code:

 uitapgesturerecognizer * taprecognizer = [[uitapgesturerecognizer alloc] initwithtarget:self action:@selector(tapgesture:)];  [self.view addgesturerecognizer:taprecognizer]; 

and define:

code:

  - (void)tapgesture:(uitapgesturerecognizer *)recognizer {     cgpoint point1 = [recognizer locationinview:recognizer.view];         uigraphicsbeginimagecontext(recognizer.view.bounds.size);     cgcontextref context = uigraphicsgetcurrentcontext();     [recognizer.view.layer renderincontext:context];         int bpr = (int)cgbitmapcontextgetbytesperrow(context);             unsigned char data = cgbitmapcontextgetdata(context);        if (data != null)     {         int offset = bpr*round(point1.y) + 4*round(point1.x);         int blue = data[offset+0];         int green = data[offset+1];         int red = data[offset+2];         int alpha =  data[offset+3];                 nslog(@"%d %d %d %d", alpha, red, green, blue);                 if (alpha == 0)         {             // here tap out of text         }         else         {             // here tap right text         }     }         uigraphicsendimagecontext();    } 

error on cgbitmapcontextgetdata

code:

  cannot initialize variable of type 'unsigned char *' r value of type 'void *'  

and not know how change it.

 

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