A few issues with this project under XCode 4.3.3 on 10.7.5
*in CalcOperation.m
compiler warning "plain _Complex requires a type specifier, assuming ‘_Complex double’"
the sample code has “_Complex long double z,c;”
*in AppDelegate.m
@synthesize bitmapView = _bitmapView;
@synthesize statusLine = _statusLine;
compiler error (red) states Existing ivar ‘_statusLine’ for property ‘statusLine’ with assign attribute must be __unsafe_unretained
or change property from “assign” to “weak” (as shown in sample code) and also remove the lines in the @interface of _bitmapView and _statusLine