setValue：forKey与_sigtramp一起崩溃

Question

The trace is like this

Application received signal SIGSEGV

Stack trace:
#0  CoreFoundation                      002BCE149F <redacted>()
#1  libobjc.A.dylib                     00394F8C8B objc_exception_throw()
#2  CoreFoundation                      002BCE13E5 -[NSException initWithCoder:]
#3  funadhoc                            000025B129 UmengSignalHandler()
#4  libsystem_platform.dylib            0039BB8873 _sigtramp()
#5  libobjc.A.dylib                     0039505571 objc_setProperty_nonatomic_copy()
#6  Foundation                          002C947F59 -[NSObject setValue:forKey:]
#7  Foundation                          002C9C58F3 -[NSObject setValuesForKeysWithDictionary:]
..........................

I understand the situation of setValue:forUndefinedKey: or setNilValueForKey: , but what is this?

Besides, some system symbols are <redacted> , how can I get it symbolicated?

Answer 1

In this case, _sigtramp() means that your application received a Unix signal, in this case SIGSEGV. SIGSEGV means that your app was sent this signal because of a memory access violation. In this case, I'm guessing it was caused by your call to setValue: forKey:. Perhaps the object you called setValue:forKey: on (the receiver of that method) has already been deallocated? Or perhaps either the key or the value has been deallocated? That's probably what you should check.

Try turning on NSZombieEnabled (environment variable). It will keep the object around and marked as a "Zombie" and then report to you that you tried to access a Zombie. If you are using ARC, you may have some unsafe-unretained reference to the object. You need to have a strong reference to it. If its non-ARC, then you probably failed to retain it properly.