title: iPhone app crashes in device but it is working in simulator
body: <p>i am working on a chat application .i used XMPP to implement this apps. it is working fine.when i want to restrict the user login in multiple device (same user ) .this is also working in simulator.but when i used device apps crashed and not showing any exception in log window( output window) .but Xcode control reached on that point</p>
  
  <pre><code>libobjc.A.dylib`objc_msgSend:
  
  0x39f07b20:  cbz    r0, 0x39f07b5e            ; objc_msgSend + 62
  0x39f07b22:  ldr.w  r9, [r0]
  0x39f07b26:  ldrh.w r12, [r9, #12]
  0x39f07b2a:  ldr.w  r9, [r9, #8]
  0x39f07b2e:  and.w  r12, r12, r1
  0x39f07b32:  add.w  r9, r9, r12, lsl #3
  0x39f07b36:  ldr.w  r12, [r9]
  0x39f07b3a:  teq.w  r12, r1
  0x39f07b3e:  bne    0x39f07b46                ; objc_msgSend + 38
  0x39f07b40:  ldr.w  r12, [r9, #4]
  0x39f07b44:  bx     r12
  0x39f07b46:  cmp.w  r12, #1
  0x39f07b4a:  blo    0x39f07b58                ; objc_msgSend + 56
  0x39f07b4c:  it     eq
  0x39f07b4e:  ldreq.w r9, [r9, #4]
  0x39f07b52:  ldr    r12, [r9, #8]!
  0x39f07b56:  b      0x39f07b3a                ; objc_msgSend + 26
  0x39f07b58:  ldr.w  r9, [r0]
  0x39f07b5c:  b      0x39f07da0                ; _objc_msgSend_uncached
  0x39f07b5e:  mov.w  r1, #0
  0x39f07b62:  bx     lr
  0x39f07b64:  nop    
  0x39f07b66:  nop    
  0x39f07b68:  nop    
  0x39f07b6a:  nop    
  0x39f07b6c:  nop    
  0x39f07b6e:  nop    
  0x39f07b70:  nop    
  0x39f07b72:  nop    
  0x39f07b74:  nop    
  0x39f07b76:  nop    
  0x39f07b78:  nop    
  0x39f07b7a:  nop    
  0x39f07b7c:  nop    
  0x39f07b7e:  nop  
  
    i don't know what is the problem .can some one help to solve this issue
  </code></pre>