Presenting ViewController

filippocld

Sorry for the stupid question but i don't know how to present a view controller using objc_util.
Can someone help me?
Thanks in Advance,
Filippo

omz

The first thing you'll need is a view controller you can present from. In most cases, the root view controller of the key window will do. You can get it like this:

root_vc = UIApplication.sharedApplication().keyWindow().rootViewController()

Note however that presenting from the root view controller will fail if it is already presenting some other view controller. This may be the case if the settings are shown or something like that. You could get around it like this:

while root_vc.presentedViewController():
    root_vc = root_vc.presentedViewController()

Once you have a presenting view controller, you can call presentViewController_animated_completion_:

my_vc = ... # assuming you have a view controller you want to present
root_vc.presentViewController_animated_completion_(my_vc, True, None)

For now, just always pass None for the completion parameter. animated can be True or False, depending on whether you want a transition animation.

You can tweak the presentation by setting your view controller's modalPresentationStyle and modalTransitionStyle properties. E.g. to present the view controller in the "form sheet" style, use

my_vc.setModalPresentationStyle_(2)

JonB

I think your best option is to grab the view controller of a presented ui.View, and add your new controllers view as a subview, and there are a fw other methods to make sure the childcontroller is set up right. Here is a method to grab the currently presented view controller:

# coding: utf-8
from objc_util import *
def get_view_controller(uiview):
   if isinstance(uiview,ui.View):
      viewobj=ObjCInstance(uiview)
   elif isa(uiview,'ObjCInstance') and uiview.isKindOfClass_(ObjCClass('UIView')):
      viewobj=uiview
   viewResponder=viewobj.nextResponder()
   try:
      while not viewResponder.isKindOfClass_(ObjCClass('UIViewController')):
         viewResponder=viewResponder.nextResponder()
      except AttributeError:
         return None #if view is not being presented for example
   return viewResponder

note this only works if the ui.View is being presented at the time.
complete example might look like

root_view_controller= get_view_controller(root)
someothercontroller.view().setFrame_(ObjCInstance(root).bounds())
ObjCInstance(root).addSubview_(someothercontroller.view())
root_view_controller.addChildViewVontroller(someothercontroller)
someothercontroller.didMoveToParentViewController_(root_view_controller)

you may also need to do some cleanup when the view is closed, but not sure...

filippocld

Ok, i was trying to do this without any help but i'm stuck.
I basically have this code

from objc_util import *
from time import sleep
#import objutil

ObjCClass('NSBundle').bundleWithPath_('/System/Library/Frameworks/ReplayKit.framework').load()

recorder=ObjCClass('RPScreenRecorder')
preview=ObjCClass('RPPreviewViewController')
sharedrecorder=recorder.sharedRecorder()
sharedrecorder.startRecordingWithMicrophoneEnabled_handler_(False,None)#(false,none)

print 'Recording:' + str(sharedrecorder.isRecording())
print 'Microphone Enabled:' + str(sharedrecorder.isMicrophoneEnabled())
sleep(3)
#Some cool things...

#Stopping the recording and saving
print 'Stopping...'
sharedrecorder.stopRecordingWithHandler_(preview)
app = ObjCClass('UIApplication').sharedApplication()
rootvc=app.keyWindow().rootViewController()
rootvc.presentViewController_animated_completion_(preview, True, None)

That "implements" a iOS 9 API (ReplayKit) and records the screen for a certain time (3 secs in this case) and then it has to present the preview view controller. But the app crashes.

Can someone help me (again)?
Thanks in advance
Filippo

omz

The problem is, you pass a view controller class to stopRecordingWithHandler_, but it expects a block... With the current beta, it's pretty difficult to make this work at all (blocks aren't really supported), but I can show you an example when the new build is up on TestFlight (probably later today). As it happens, I've been experimenting with exactly this API as well...

filippocld

Thanks, waiting for it :-)

omz

Okay, here's a minimal example that shows how you can use RPScreenRecorder – as I said, it'll only work with the latest build (#160023), so please install that first.

Note to others who might be reading this: You also need to have the iOS 9 beta installed for this to work.

from objc_util import *
import time

NSBundle = ObjCClass('NSBundle')
replaykit = NSBundle.bundleWithPath_('/System/Library/Frameworks/ReplayKit.framework')
replaykit.load()

RPScreenRecorder = ObjCClass('RPScreenRecorder')

def stop_callback(_cmd, _vc):
	vc = ObjCInstance(_vc)
	rootvc = UIApplication.sharedApplication().keyWindow().rootViewController()
	vc.popoverPresentationController().setSourceView_(rootvc.view())
	rootvc.presentViewController_animated_completion_(vc, True, None)

stop_handler = ObjCBlock(stop_callback, restype=None, argtypes=[c_void_p, c_void_p])

recorder = RPScreenRecorder.sharedRecorder()

@on_main_thread
def start_recording():
	recorder.startRecordingWithMicrophoneEnabled_handler_(False, None)

@on_main_thread
def stop_recording():
	recorder.stopRecordingWithHandler_(stop_handler)

start_recording()
time.sleep(5)
stop_recording()

filippocld

Thanks.
What is @on_main_thread for?

omz

What is @on_main_thread for?

I think it's not strictly necessary here, but most things that have to do with UI need to be called from the main thread.

filippocld

It crashes :-( i copied exactly what you wrote and crashes 😱

omz

Hmm. What kind of device do you have? Could be that it doesn't work on 32 bit...

filippocld

Ipad air 2, it is 64 bit. I noticed removing on main thread crashes the app after the recording and before the presentation, leaving it crashes when start_recording() is called

omz

Okay, no idea what might be causing the crash then, sorry. :/

It doesn't crash here at all, but I've noticed that the resulting videos contain strange artifacts (looks like tearing), not sure if that's related somehow.

filippocld

Ok, will try to solve it by me :-/
If you find something that could cause crashes tell me

filippocld

I'm near to the solution.
I removed @on_main_thread (that crashes many scripts i already worked on and worked with previous beta) and i tried to experiment with ObjCBlocks, always with a crash. So downloaded the example in the docs about the blocks. Guess what? It Crashes! The crash definitely has to do with blocks

Hope this helps solving the bug,
Filippo

omz

I'll do some more testing. It might have to do with different build settings in the TestFlight version vs. my local development build – after all, the code I posted definitely works here, and I don't think hardware differences are responsible for this (iPad Air 1 vs. 2 aren't that different).

I think this particular use case is possible to do without blocks (using a delegate instead), but it would still be nice if I could get those to work reliably.

filippocld

Thanks :-)
Did some (more and more) testing with the example file and found that maybe the line 14 (where the handler is called) is responsible for the crash

ywangd

I can run the example block code (sorting function) from the documentation. My device is also a iPad Air 2.

The RPScreenRecorder did NOT run but it was due to a different error. The replaykit was not created successfully. The bundleWithPath_ method returned a None for me.

filippocld

Your error is there because you have iOS 8. ReplayKit is a framework of iOS 9.

Dunno about the example, maybe is some iOS 9 bug

@omz I was wrong, the line that crashes the app is line 14, where you call the handler. Anyway @on_main_thread crashes too for me. Remember i am on iPad Air 2 WiFi iOS 9 beta 5

filippocld

Ok, @omz in the meantime can you show me how to do with delegates, please? :-)
Would be much appreciated