Lock screen on device programmatically - ios

Question

I have read the other questions regarding the same, but everyone is just saying 'Jailbreak', 'that'll never be approved by Apple', 'It's not possible' and 'private API, GraphicsServices.framework'.
Let me just clear something up, I am not doing this for a jailbroken phone, I am doing this because the lock-button on my phone is broken, and I simply want to not have to wait 1 minute for the screen to lock. So I figured I could have an app which called lockScreen in the beginning of AppDelegate.h. This is not going on AppStore, it's just for me.
I've seen people saying they can use GSEventLockDevice(); when importing GSEvent.h from GraphicsServices.framework, but when I try running it (both on device and simulator) I get this, and it won't build:
Undefined symbols for architecture armv7s:
"_GSEventLockDevice", referenced from:
-[AppDelegate application:didFinishLaunchingWithOptions:] in AppDelegate.o
ld: symbol(s) not found for architecture armv7s
clang: error: linker command failed with exit code 1 (use -v to see invocation)
I'm not completely sure what this means. If I remove the line GSEventLockDevice(); but still import GSEvent.h, everything is running fine.
Does my device need to be jailbroken for this to work or something?

Answer 1

This has already been resolved by somebody else. You can find it on Github: https://github.com/neuroo/LockMeNow
char *gsDylib = "/System/Library/PrivateFrameworks/GraphicsServices.framework/GraphicsServices";
void *handle = dlopen(gsDylib, RTLD_NOW);
if (handle) {
BOOL locked = FALSE;
void (*_GSEventLockDevice)() = dlsym(handle, "GSEventLockDevice");
if (_GSEventLockDevice) {
_GSEventLockDevice();
//...
}
dlclose(handle);
//...
}

Answer 2

There is no reason to code an app to lock your phone. Use Assistive Touch in Accessibility settings to accomplish hardware button tasks from a button on screen. This button is accessible on screen (but can be easily hidden) from anywhere on the phone, where as your "lock app" is only accessible from the home screen. Check out this support article. Trust me, my lock button is broken too.

Answer 3

You are getting the undefined symbol error because you are not linking to the private framework in your app. It needs to be included in your Build Phases Link Binary with Libraries step.
Since GraphicsServices.framework is not a public framework, it won't show up in the frameworks list. I found this answer that gives steps to link to a private framework. I haven't tried it, so YMMV.
How do I add the following private frameworks to my iPhone app?