parallax - addObserver:forKeyPath is crashing the app, KVO, objective c -

i doing parallax effect using category doing :

    add , uiview uitableview (via category     add addobserver:forkeypath whenever tableview moving, reframe view above 

details below uiscrollview+parallax.h

    #import <uikit/uikit.h>      @class parallaxview;     @interface uiscrollview (parallax)      @property (strong, nonatomic)   parallaxview    *parallaxview;     - (void) addparallaxviewwith:(uiview*)parallaxview;     - (void) removekvo;      @end       @interface parallaxview : uiview      @end 

uiscrollview+parallax.m

static char parallaxkey;     @implementation uiscrollview (parallax)     @dynamic parallaxview;       #pragma mark - add parallax view scrollview     - (void) addparallaxviewwith:(parallaxview*)pview {         if ( !self.parallaxview) {              [self addsubview:pview];             [self setparallaxview:pview];         }      }      #pragma mark - set parallaxview + register parallaxview observer     - (void) setparallaxview:(parallaxview *)parallaxview {         objc_setassociatedobject(self, &parallaxkey, parallaxview, objc_association_assign);     /* these line crashing app */     //    [self addobserver:self.parallaxview     //           forkeypath:@"contentoffset"     //              options:nskeyvalueobservingoptionnew     //              context:nil];     }      #pragma mark - parallaxview     - (parallaxview*) parallaxview {         return (objc_getassociatedobject(self, &parallaxkey));     }     #pragma mark - remove      - (void)removekvo {             [self removeobserver:self.parallaxview forkeypath:@"contentoffset"];     }      @end      @implementation parallaxview      -(id)init     {         //load xib main bundle , assign self         self = [[[nsbundle mainbundle]loadnibnamed:@"parallex"                                              owner:self                                            options:nil] objectatindex:0];          return self;     }      -(id)initwithframe:(cgrect)frame     {         self = [self init];         [self setframe:frame];          return self;     }     ................      @end 

and adding parallax table doing

parallaxview *pview = [[parallaxview alloc]initwithframe:cgrectmake(0, 0, 320, 160)];  [self.tableview addparallaxviewwith:pview]; 

however, [self addobserver:forkeypath:options:context:nil] keeps crashing app without no clues @ all. if comments line out , app not crashing parallex effect not working.

any ideas problematics. please help. thanks

problem in code

 -(id)initwithframe:(cgrect)frame     {         self = [self init];         [self setframe:frame];          return self;     } 

in above code self = [self init]; , [self setframe:frame]; go in recursion give crash ,first fix guess solve problem,it should this

- (id)initwithframe:(cgrect)frame {     self = [super initwithframe:frame];     if (self) {         // initialization code     }     return self; } 

and loading view nib using

self = [[[nsbundle mainbundle]loadnibnamed:@"parallex"                                              owner:self                                            options:nil] objectatindex:0]; 

this code bad idea. can refer this task. happy , clean coding...