@mikael
@cvp
Thank you. I'm working on finishing my clipboard plan now. Thank you for your help. I have learned a lot!

@cvp
Usually the second run has an error，maybe it's after first completion......

@cvp
This is Apple's UI design. The completion handler is asynchronous and runs immediately.
"ItemProvider. Loadobjectofclass_completionhandler_()" returns a progress, which can cancel operations or obtain progress data. During this period, developers can design a set of suitable UI animation to reduce the waiting experience of users, or cancel loading.

@cvp
ok...we won

# coding: utf-8
from objc_util import *
import ui,time

def dropInteraction_canHandleSession_(_m,_c,interaction,session):
    return True
def dropInteraction_sessionDidUpdate_(_m,_c,interaction,session):
    return ObjCClass('UIDropProposal').alloc().initWithDropOperation(2).ptr
    
def dropInteraction_performDrop_(_m,_c,interaction,session):
    session=ObjCInstance(session)
    def handler(_cmd,obj_ptr):
        obj=ObjCInstance(obj_ptr)
        print(obj)
        
    handler_block = ObjCBlock(handler, restype=None, argtypes=[c_void_p,c_void_p])
    def ptimer(progress):
        while True:
            if(progress.totalUnitCount()==progress.completedUnitCount()):
                break
            time.sleep(0.1)
    for item in session.items():
        itemProvider =item.itemProvider()
        uiimage =ObjCClass('UIImage')
        
        if(itemProvider.canLoadObjectOfClass(uiimage)):
            progress=itemProvider.loadObjectOfClass_completionHandler_(ObjCClass('UIImage'),handler_block)
            ptimer(progress)
        elif(itemProvider.canLoadObjectOfClass(NSString)):
            progress=itemProvider.loadObjectOfClass_completionHandler_(NSString,handler_block)
            ptimer(progress)
            
        else:
            print(itemProvider)
            
methods=[dropInteraction_canHandleSession_,dropInteraction_sessionDidUpdate_,dropInteraction_performDrop_]
protocols=['UIDropInteractionDelegate']
dropDelegate=create_objc_class('MydropDelegate',methods=methods,protocols=protocols)


Delegate=dropDelegate.alloc().init()
dropInteraction=ObjCClass('UIDropInteraction').alloc().initWithDelegate(Delegate)

drop_view = ui.View(bg_color='blue')
drop_view.objc_instance.setUserInteractionEnabled(True)
drop_view.objc_instance.addInteraction(dropInteraction)
drop_view.present()

@cvp
jonb said ：
the Pythonista hava two threads
1.The main thread, or ui thread
2.The interpreter thread

I don't know if the error is related to IOS thread.
but I remember that the apple development document said that the NSItemProvider interface should be used in DispatchQueue.main.async { }

I'm learning something about it..

@cvp
There will be an error message：TypeError..

# coding: utf-8
from objc_util import *
import ui

def dropInteraction_canHandleSession_(_m,_c,interaction,session):
    return True
def dropInteraction_sessionDidUpdate_(_m,_c,interaction,session):
    return ObjCClass('UIDropProposal').alloc().initWithDropOperation(2).ptr
    
def dropInteraction_performDrop_(_m,_c,interaction,session):
    session=ObjCInstance(session)
    def handler(_cmd,obj_ptr):
        obj=ObjCInstance(obj_ptr)
        print(obj)
    handler_block = ObjCBlock(handler, restype=None, argtypes=[c_void_p,c_void_p])
    
    for item in session.items():
        itemProvider =item.itemProvider()
        uiimage =ObjCClass('UIImage')
        nsstring =ObjCClass('NSString')
        if(itemProvider.canLoadObjectOfClass(uiimage)):
            on_main_thread(itemProvider.loadObjectOfClass_completionHandler_(ObjCClass('UIImage'),handler_block))
        elif(itemProvider.canLoadObjectOfClass(nsstring)):
            on_main_thread(itemProvider.loadObjectOfClass_completionHandler_(nsstring,handler_block))
        else:
            continue
            
methods=[dropInteraction_canHandleSession_,dropInteraction_sessionDidUpdate_,dropInteraction_performDrop_]
protocols=['UIDropInteractionDelegate']
dropDelegate=create_objc_class('MydropDelegate',methods=methods,protocols=protocols)


Delegate=dropDelegate.alloc().init()
dropInteraction=ObjCClass('UIDropInteraction').alloc().initWithDelegate(Delegate)

drop_view = ui.View(bg_color='blue',frame=(0,0,500,500))
drop_view.objc_instance.setUserInteractionEnabled(True)
drop_view.objc_instance.addInteraction(dropInteraction)
drop_view.present()

@cvp
ok....I should have avoided this mistake long ago...
Just let this asynchronous function run on the main thread. Everything is normal, no flashbacks, and no errors........

@cvp
The first call successfully gets the dragged data, but the second flash back. I'm trying to resolve this error.The error log is

Fatal Python error: Segmentation fault

Thread 0x000000016fc77000 (most recent call first):

@cvp
drag already written
and drop already written, too
but Random crashes have no error log

@cvp
link img

This is my work of art. Please don't laugh