Swift: A function with a Selector argument returns an unmanaged?












5















What is the use of -



func perform(_ aSelector: Selector!) -> unmanaged<AnyObject>!



in iOS?




  • To call a method of a class?

  • To add a selector method?

  • To add a class delegate?

  • To define a class? (I doubt it's this)


I was originally thinking that it it was to add a selector method, but after looking at it some more I think it may be "to call a method of a class." Selectors are used for target/action paradigms where I kick something off and when the event fires or finishes then it wants to fire off some kind of action method.
In this example do I pass it a parameter of a selector function then at the end of this "perform" function, I am returning an unmanaged object of any type? Does that even make sense?



Thanks!






ios swift







share|improve this question























  • Are you referring to the method from NSObjectProtocol which is from the Objective-C runtime?

    – rmaddy
    Nov 14 '18 at 23:41











  • @rmaddy --> I don't know. This was asked on a quiz that I was taking and I didn't have any other information for this question.

    – TSuperman
    Nov 14 '18 at 23:49











  • @rmaddy -> If the method was referring to the NSObjectProtocol, would it have a different meaning or do something that I wouldn't normally expect?

    – TSuperman
    Nov 15 '18 at 0:01






  • 1





    Basically it's something you would very rarely, if ever, use in Swift. It should rarely be used directly any more in Objective-C.

    – rmaddy
    Nov 15 '18 at 0:03








  • 1





    Indeed this used to be forbidden in Swift, and even now should be avoided, as Swift provides better ways. See stackoverflow.com/questions/24158427/… for example

    – matt
    Nov 15 '18 at 0:55
















5















What is the use of -



func perform(_ aSelector: Selector!) -> unmanaged<AnyObject>!



in iOS?




  • To call a method of a class?

  • To add a selector method?

  • To add a class delegate?

  • To define a class? (I doubt it's this)


I was originally thinking that it it was to add a selector method, but after looking at it some more I think it may be "to call a method of a class." Selectors are used for target/action paradigms where I kick something off and when the event fires or finishes then it wants to fire off some kind of action method.
In this example do I pass it a parameter of a selector function then at the end of this "perform" function, I am returning an unmanaged object of any type? Does that even make sense?



Thanks!






ios swift







share|improve this question























  • Are you referring to the method from NSObjectProtocol which is from the Objective-C runtime?

    – rmaddy
    Nov 14 '18 at 23:41











  • @rmaddy --> I don't know. This was asked on a quiz that I was taking and I didn't have any other information for this question.

    – TSuperman
    Nov 14 '18 at 23:49











  • @rmaddy -> If the method was referring to the NSObjectProtocol, would it have a different meaning or do something that I wouldn't normally expect?

    – TSuperman
    Nov 15 '18 at 0:01






  • 1





    Basically it's something you would very rarely, if ever, use in Swift. It should rarely be used directly any more in Objective-C.

    – rmaddy
    Nov 15 '18 at 0:03








  • 1





    Indeed this used to be forbidden in Swift, and even now should be avoided, as Swift provides better ways. See stackoverflow.com/questions/24158427/… for example

    – matt
    Nov 15 '18 at 0:55














5












5








5


0






What is the use of -



func perform(_ aSelector: Selector!) -> unmanaged<AnyObject>!



in iOS?




  • To call a method of a class?

  • To add a selector method?

  • To add a class delegate?

  • To define a class? (I doubt it's this)


I was originally thinking that it it was to add a selector method, but after looking at it some more I think it may be "to call a method of a class." Selectors are used for target/action paradigms where I kick something off and when the event fires or finishes then it wants to fire off some kind of action method.
In this example do I pass it a parameter of a selector function then at the end of this "perform" function, I am returning an unmanaged object of any type? Does that even make sense?



Thanks!






ios swift







share|improve this question














What is the use of -



func perform(_ aSelector: Selector!) -> unmanaged<AnyObject>!



in iOS?




  • To call a method of a class?

  • To add a selector method?

  • To add a class delegate?

  • To define a class? (I doubt it's this)


I was originally thinking that it it was to add a selector method, but after looking at it some more I think it may be "to call a method of a class." Selectors are used for target/action paradigms where I kick something off and when the event fires or finishes then it wants to fire off some kind of action method.
In this example do I pass it a parameter of a selector function then at the end of this "perform" function, I am returning an unmanaged object of any type? Does that even make sense?



Thanks!






ios swift




ios swift






share|improve this question













share|improve this question











share|improve this question




share|improve this question










asked Nov 14 '18 at 23:35









TSupermanTSuperman

485




485













  • Are you referring to the method from NSObjectProtocol which is from the Objective-C runtime?

    – rmaddy
    Nov 14 '18 at 23:41











  • @rmaddy --> I don't know. This was asked on a quiz that I was taking and I didn't have any other information for this question.

    – TSuperman
    Nov 14 '18 at 23:49











  • @rmaddy -> If the method was referring to the NSObjectProtocol, would it have a different meaning or do something that I wouldn't normally expect?

    – TSuperman
    Nov 15 '18 at 0:01






  • 1





    Basically it's something you would very rarely, if ever, use in Swift. It should rarely be used directly any more in Objective-C.

    – rmaddy
    Nov 15 '18 at 0:03








  • 1





    Indeed this used to be forbidden in Swift, and even now should be avoided, as Swift provides better ways. See stackoverflow.com/questions/24158427/… for example

    – matt
    Nov 15 '18 at 0:55



















  • Are you referring to the method from NSObjectProtocol which is from the Objective-C runtime?

    – rmaddy
    Nov 14 '18 at 23:41











  • @rmaddy --> I don't know. This was asked on a quiz that I was taking and I didn't have any other information for this question.

    – TSuperman
    Nov 14 '18 at 23:49











  • @rmaddy -> If the method was referring to the NSObjectProtocol, would it have a different meaning or do something that I wouldn't normally expect?

    – TSuperman
    Nov 15 '18 at 0:01






  • 1





    Basically it's something you would very rarely, if ever, use in Swift. It should rarely be used directly any more in Objective-C.

    – rmaddy
    Nov 15 '18 at 0:03








  • 1





    Indeed this used to be forbidden in Swift, and even now should be avoided, as Swift provides better ways. See stackoverflow.com/questions/24158427/… for example

    – matt
    Nov 15 '18 at 0:55

















Are you referring to the method from NSObjectProtocol which is from the Objective-C runtime?

– rmaddy
Nov 14 '18 at 23:41





Are you referring to the method from NSObjectProtocol which is from the Objective-C runtime?

– rmaddy
Nov 14 '18 at 23:41













@rmaddy --> I don't know. This was asked on a quiz that I was taking and I didn't have any other information for this question.

– TSuperman
Nov 14 '18 at 23:49





@rmaddy --> I don't know. This was asked on a quiz that I was taking and I didn't have any other information for this question.

– TSuperman
Nov 14 '18 at 23:49













@rmaddy -> If the method was referring to the NSObjectProtocol, would it have a different meaning or do something that I wouldn't normally expect?

– TSuperman
Nov 15 '18 at 0:01





@rmaddy -> If the method was referring to the NSObjectProtocol, would it have a different meaning or do something that I wouldn't normally expect?

– TSuperman
Nov 15 '18 at 0:01




1




1





Basically it's something you would very rarely, if ever, use in Swift. It should rarely be used directly any more in Objective-C.

– rmaddy
Nov 15 '18 at 0:03







Basically it's something you would very rarely, if ever, use in Swift. It should rarely be used directly any more in Objective-C.

– rmaddy
Nov 15 '18 at 0:03






1




1





Indeed this used to be forbidden in Swift, and even now should be avoided, as Swift provides better ways. See stackoverflow.com/questions/24158427/… for example

– matt
Nov 15 '18 at 0:55





Indeed this used to be forbidden in Swift, and even now should be avoided, as Swift provides better ways. See stackoverflow.com/questions/24158427/… for example

– matt
Nov 15 '18 at 0:55












1 Answer
1






active

oldest

votes


















3














In Swift this is basically useless. It's bridged from Objective-C, where it used to be very useful (before ARC), but now it's a bit tricky.



The point of it is to send a message by name and get a result. Generally speaking that translates to calling a method of that name.






share|improve this answer
























  • So basically this is "calling a method" and returning some data type? Not a nice way of doing it, but a long, obnoxious way of doing it?

    – TSuperman
    Nov 14 '18 at 23:44






  • 1





    It's only obnoxious in Swift. In ObjC, it's pretty elegant, and is the core tool used for all the target/action features like UIButton, NSTimer, and the like.

    – Rob Napier
    Nov 15 '18 at 0:02











  • Thanks! I have been writing more Swift code than Objective-C.

    – TSuperman
    Nov 15 '18 at 0:42











  • Is this method just short-hand for the ObjC runtime APIs like class_getMethodImplementation(AnyClass?, Selector)?

    – Alexander
    Nov 15 '18 at 1:37






  • 1





    @Alexander It's a wrapper around objc_msgSend. You can see the source code for it here: opensource.apple.com/source/objc4/objc4-723/runtime/…

    – Rob Napier
    Nov 15 '18 at 13:46











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1 Answer
1






active

oldest

votes








1 Answer
1






active

oldest

votes









active

oldest

votes






active

oldest

votes









3














In Swift this is basically useless. It's bridged from Objective-C, where it used to be very useful (before ARC), but now it's a bit tricky.



The point of it is to send a message by name and get a result. Generally speaking that translates to calling a method of that name.






share|improve this answer
























  • So basically this is "calling a method" and returning some data type? Not a nice way of doing it, but a long, obnoxious way of doing it?

    – TSuperman
    Nov 14 '18 at 23:44






  • 1





    It's only obnoxious in Swift. In ObjC, it's pretty elegant, and is the core tool used for all the target/action features like UIButton, NSTimer, and the like.

    – Rob Napier
    Nov 15 '18 at 0:02











  • Thanks! I have been writing more Swift code than Objective-C.

    – TSuperman
    Nov 15 '18 at 0:42











  • Is this method just short-hand for the ObjC runtime APIs like class_getMethodImplementation(AnyClass?, Selector)?

    – Alexander
    Nov 15 '18 at 1:37






  • 1





    @Alexander It's a wrapper around objc_msgSend. You can see the source code for it here: opensource.apple.com/source/objc4/objc4-723/runtime/…

    – Rob Napier
    Nov 15 '18 at 13:46
















3














In Swift this is basically useless. It's bridged from Objective-C, where it used to be very useful (before ARC), but now it's a bit tricky.



The point of it is to send a message by name and get a result. Generally speaking that translates to calling a method of that name.






share|improve this answer
























  • So basically this is "calling a method" and returning some data type? Not a nice way of doing it, but a long, obnoxious way of doing it?

    – TSuperman
    Nov 14 '18 at 23:44






  • 1





    It's only obnoxious in Swift. In ObjC, it's pretty elegant, and is the core tool used for all the target/action features like UIButton, NSTimer, and the like.

    – Rob Napier
    Nov 15 '18 at 0:02











  • Thanks! I have been writing more Swift code than Objective-C.

    – TSuperman
    Nov 15 '18 at 0:42











  • Is this method just short-hand for the ObjC runtime APIs like class_getMethodImplementation(AnyClass?, Selector)?

    – Alexander
    Nov 15 '18 at 1:37






  • 1





    @Alexander It's a wrapper around objc_msgSend. You can see the source code for it here: opensource.apple.com/source/objc4/objc4-723/runtime/…

    – Rob Napier
    Nov 15 '18 at 13:46














3












3








3







In Swift this is basically useless. It's bridged from Objective-C, where it used to be very useful (before ARC), but now it's a bit tricky.



The point of it is to send a message by name and get a result. Generally speaking that translates to calling a method of that name.






share|improve this answer













In Swift this is basically useless. It's bridged from Objective-C, where it used to be very useful (before ARC), but now it's a bit tricky.



The point of it is to send a message by name and get a result. Generally speaking that translates to calling a method of that name.







share|improve this answer












share|improve this answer



share|improve this answer










answered Nov 14 '18 at 23:41









Rob NapierRob Napier

203k28299425




203k28299425













  • So basically this is "calling a method" and returning some data type? Not a nice way of doing it, but a long, obnoxious way of doing it?

    – TSuperman
    Nov 14 '18 at 23:44






  • 1





    It's only obnoxious in Swift. In ObjC, it's pretty elegant, and is the core tool used for all the target/action features like UIButton, NSTimer, and the like.

    – Rob Napier
    Nov 15 '18 at 0:02











  • Thanks! I have been writing more Swift code than Objective-C.

    – TSuperman
    Nov 15 '18 at 0:42











  • Is this method just short-hand for the ObjC runtime APIs like class_getMethodImplementation(AnyClass?, Selector)?

    – Alexander
    Nov 15 '18 at 1:37






  • 1





    @Alexander It's a wrapper around objc_msgSend. You can see the source code for it here: opensource.apple.com/source/objc4/objc4-723/runtime/…

    – Rob Napier
    Nov 15 '18 at 13:46



















  • So basically this is "calling a method" and returning some data type? Not a nice way of doing it, but a long, obnoxious way of doing it?

    – TSuperman
    Nov 14 '18 at 23:44






  • 1





    It's only obnoxious in Swift. In ObjC, it's pretty elegant, and is the core tool used for all the target/action features like UIButton, NSTimer, and the like.

    – Rob Napier
    Nov 15 '18 at 0:02











  • Thanks! I have been writing more Swift code than Objective-C.

    – TSuperman
    Nov 15 '18 at 0:42











  • Is this method just short-hand for the ObjC runtime APIs like class_getMethodImplementation(AnyClass?, Selector)?

    – Alexander
    Nov 15 '18 at 1:37






  • 1





    @Alexander It's a wrapper around objc_msgSend. You can see the source code for it here: opensource.apple.com/source/objc4/objc4-723/runtime/…

    – Rob Napier
    Nov 15 '18 at 13:46

















So basically this is "calling a method" and returning some data type? Not a nice way of doing it, but a long, obnoxious way of doing it?

– TSuperman
Nov 14 '18 at 23:44





So basically this is "calling a method" and returning some data type? Not a nice way of doing it, but a long, obnoxious way of doing it?

– TSuperman
Nov 14 '18 at 23:44




1




1





It's only obnoxious in Swift. In ObjC, it's pretty elegant, and is the core tool used for all the target/action features like UIButton, NSTimer, and the like.

– Rob Napier
Nov 15 '18 at 0:02





It's only obnoxious in Swift. In ObjC, it's pretty elegant, and is the core tool used for all the target/action features like UIButton, NSTimer, and the like.

– Rob Napier
Nov 15 '18 at 0:02













Thanks! I have been writing more Swift code than Objective-C.

– TSuperman
Nov 15 '18 at 0:42





Thanks! I have been writing more Swift code than Objective-C.

– TSuperman
Nov 15 '18 at 0:42













Is this method just short-hand for the ObjC runtime APIs like class_getMethodImplementation(AnyClass?, Selector)?

– Alexander
Nov 15 '18 at 1:37





Is this method just short-hand for the ObjC runtime APIs like class_getMethodImplementation(AnyClass?, Selector)?

– Alexander
Nov 15 '18 at 1:37




1




1





@Alexander It's a wrapper around objc_msgSend. You can see the source code for it here: opensource.apple.com/source/objc4/objc4-723/runtime/…

– Rob Napier
Nov 15 '18 at 13:46





@Alexander It's a wrapper around objc_msgSend. You can see the source code for it here: opensource.apple.com/source/objc4/objc4-723/runtime/…

– Rob Napier
Nov 15 '18 at 13:46




















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