ios - NSRecursiveLock Deallocated -

i have ios app multiple view controllers , arc enabled. 1 of view controllers has iboutlet uiscrollview , uipagecontrol. when view controller loaded error printed in console:

*** -[nsrecursivelock dealloc]: lock (<nsrecursivelock: 0xcb88cb0> '(null)')  deallocated while still in use 

while trying fix problem, created symbolic breakpoint symbol _nslockerror module set foundation. xcode breaks breakpoint 1.1 on "0x12d2b58: pushl %ebp", on thread 1.

foundation`_nslockerror: ----------------------------------------------------- |> 0x12d2b58: pushl %ebp   <|thread 1: breakpoint 1.1| ----------------------------------------------------- 0x12d2b59:  movl   %esp, %ebp 0x12d2b5b:  subl   $8, %esp 0x12d2b5e:  calll  0x12d2b63                 ; _nslockerror + 11 0x12d2b63:  popl   %eax 0x12d2b64:  leal   2118709(%eax), %eax 0x12d2b6a:  movl   %eax, (%esp) 0x12d2b6d:  calll  0x125689d                 ; nslog 0x12d2b72:  addl   $8, %esp 0x12d2b75:  popl   %ebp 0x12d2b76:  ret   

here code in application problematic viewcontroller:

header file (.h):

#import <uikit/uikit.h>  @class aboutviewcontroller;  @protocol aboutviewcontrollerdelegate  - (void)aboutviewcontrollerdidfinish:(aboutviewcontroller *)controller; @end  @interface aboutviewcontroller : uiviewcontroller<uiscrollviewdelegate>   @property (strong, nonatomic,retain) id <aboutviewcontrollerdelegate> delegate; @property (nonatomic,strong,) iboutlet uiscrollview *scrollview; @property (nonatomic, strong) iboutlet uipagecontrol *pagecontrol; @property (nonatomic, strong) nsarray *imagearray; @property(nonatomic, assign) iboutlet uilabel *label;  - (ibaction)done:(id)sender; //returns main menu after button pressed  @end 

implementation file (.m):

#import "aboutviewcontroller.h"  @interface aboutviewcontroller ()  @end  @implementation aboutviewcontroller  @synthesize scrollview; @synthesize pagecontrol; @synthesize imagearray;  int page;  - (id)initwithnibname:(nsstring *)nibnameornil bundle:(nsbundle *)nibbundleornil {     self = [super initwithnibname:nibnameornil bundle:nibbundleornil];     if (self) {         // custom initialization     }     return self; }  - (void)viewdidload {     [super viewdidload];     //load images scrollview in array     imagearray = [[nsarray alloc] initwithobjects:@"1.png", @"2.png", @"3.png", nil];      (int = 0; < [imagearray count]; i++ ) {        int page = scrollview.contentoffset.x / scrollview.frame.size.width;         cgrect frame;        frame.origin.x = self.scrollview.frame.size.width * i;        frame.origin.y = 0;        frame.size = self.scrollview.frame.size;          uiimageview *imageview = [[uiimageview alloc] initwithframe:frame];         imageview.image = [uiimage imagenamed:[imagearray objectatindex:i]];         [self.scrollview addsubview:imageview];         nslog (@"page %d",page);         if (page==0) {             self.label.text = [nsstring stringwithformat:@"%s","page1"];         }       }      scrollview.contentsize = cgsizemake(scrollview.frame.size.                                     width *[imagearray count],     scrollview.frame.size.height); }  #pragma mark - uiscrollview delegate - (void)scrollviewdidscroll:(uiscrollview *)sender {      cgfloat pagewidth = self.scrollview.frame.size.width;     //calculate current page in scrollview      int page = floor((self.scrollview.contentoffset.x - pagewidth / 2) / pagewidth) + 1;     self.pagecontrol.currentpage = page;     nslog (@"page %d",page);      if (page==0) {         //change image caption         self.label.text = [nsstring stringwithformat:@"%s","hello"];         [uiview beginanimations:nil context:null];         [uiview setanimationduration:1.0];         [_label setalpha:1];         [uiview commitanimations];     }      if (page==1) {         //change image caption          self.label.text = [nsstring stringwithformat:@"%s","world"];         [uiview beginanimations:nil context:null];         [uiview setanimationduration:1.0];         [_label setalpha:1];         [uiview commitanimations];      }      if (page==2) {         //change image caption         self.label.text = [nsstring stringwithformat:@"%s","foobar"];         [uiview beginanimations:nil context:null];         [uiview setanimationduration:1.0];         [_label setalpha:1];         [uiview commitanimations];        }  }  - (ibaction)done:(id)sender {     [self.delegate aboutviewcontrollerdidfinish:self];  }  @end 

after (lldb)bt:

 * thread #1: tid = 0x1c8f63, 0x012d2b58 foundation`_nslockerror, queue = 'com.apple.main-thread, stop reason = breakpoint 1.1         frame #0: 0x012d2b58 foundation`_nslockerror         frame #1: 0x01247153 foundation`-[nsrecursivelock dealloc] + 159         frame #2: 0x01820692 libobjc.a.dylib`objc_object::sidetable_release(bool) + 268         frame #3: 0x01821adf libobjc.a.dylib`-[nsobject release] + 25         frame #4: 0x05a89385 uifoundation`_freeextradata + 48         frame #5: 0x05a895d5 uifoundation`-[nslayoutmanager dealloc] + 381         frame #6: 0x01820692 libobjc.a.dylib`objc_object::sidetable_release(bool) + 268         frame #7: 0x01821adf libobjc.a.dylib`-[nsobject release] + 25         frame #8: 0x00a91065 uikit`-[uitextview dealloc] + 168         frame #9: 0x00453e6b uikit`-[uiview release] + 89         frame #10: 0x0045f2d4 uikit`-[uiview(hierarchy) removefromsuperview] + 292         frame #11: 0x0047b4fd uikit`-[uiscrollview removefromsuperview] + 84         frame #12: 0x004565db uikit`-[uiview dealloc] + 432         frame #13: 0x00477eaf uikit`-[uiscrollview dealloc] + 1156         frame #14: 0x00453e6b uikit`-[uiview release] + 89         frame #15: 0x0045f2d4 uikit`-[uiview(hierarchy) removefromsuperview] + 292         frame #16: 0x0047b4fd uikit`-[uiscrollview removefromsuperview] + 84         frame #17: 0x004565db uikit`-[uiview dealloc] + 432         frame #18: 0x00453e6b uikit`-[uiview release] + 89         frame #19: 0x01ba2380 corefoundation`cfrelease + 272         frame #20: 0x01bc18b4 corefoundation`-[__nsarraym dealloc] + 196         frame #21: 0x01820692 libobjc.a.dylib`objc_object::sidetable_release(bool) + 268         frame #22: 0x0181fe81 libobjc.a.dylib`objc_release + 49         frame #23: 0x01820ce7 libobjc.a.dylib`(anonymous      namespace)::autoreleasepoolpage::pop(void*) + 537         frame #24: 0x01bc1fc8 corefoundation`_cfautoreleasepoolpop + 24         frame #25: 0x00402c6e uikit`_wraprunloopwithautoreleasepoolhandler + 59         frame #26: 0x01be89ee     corefoundation`__cfrunloop_is_calling_out_to_an_observer_callback_function__ + 30         frame #27: 0x01be893f corefoundation`__cfrunloopdoobservers + 399         frame #28: 0x01bc6cb0 corefoundation`__cfrunlooprun + 1936         frame #29: 0x01bc610d corefoundation`cfrunlooprunspecific + 445         frame #30: 0x01bc5f3b corefoundation`cfrunloopruninmode + 123         frame #31: 0x032e2ff2 graphicsservices`gseventrunmodal + 192         frame #32: 0x032e2e19 graphicsservices`gseventrun + 104         frame #33: 0x004054eb uikit`uiapplicationmain + 1225         frame #34: 0x0000789d monarch`main(argc=1, argv=0xbfffee1c) + 141 @ main.m:16 

my question why nsrecursivelock deallocated in first place?

i never mentioned nsrecursivelock in code. there similar question on not detailed.

does arc come play here?

i don't know if related problem, think properties not correctly configured. recommended use "weak" , not "strong" or "assign" "iboutlet" properties (usually outlet subview of view controller's "view" property, these subviews retained "view" property).

also have delegate using strong , retain, don't need both, since you're using arc, use "strong" keyword only, , don't use "retain" anymore. , way, since delegate, should use "weak" property in order avoid circular reference.