EXEC_BAD_ACCESS (code=10 address=0x1000800) after method execution got over

EXEC_BAD_ACCESS (code=10 address=0x1000800) after method execution got over

I am using PDFTron for drawing annotations. In DrawAnnotation method i
have written code for drawing annotation. Once the execution of this
method get over my app crashes. The crash is because of EXEC_BAD_ACCESS
(code=10 address=0x1000800). Can any one help me why it is happening ?
Note- App is crashing sometimes,not each time i draw an annotation.