A common means for (un)related objects to communicate with each other.
Questions tagged [protocols]
5592 questions
94
votes
1 answer
Can a category implement a protocol in Objective C?
I have a category on NSDate and it would be convenient if it could implement a protocol I previously created. Is this possible? what's the correct syntax for this?
cfischer
- 24,452
- 37
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94
votes
5 answers
What is SOCK_DGRAM and SOCK_STREAM?
I just came across this strange thing I got to see application is that by default they use SOCK_STREAM function. Why is it so? Is this SOCK_STREAM just creating multiple streams? Or is it the standard SOCK_STREAM function available for creating…
echo9
- 1,159
- 1
- 13
- 15
93
votes
13 answers
How to detect browser's protocol handlers?
I have created a custom URL protocol handler.
http://
mailto://
custom://
I have registered a WinForms application to respond accordingly. This all works great.
But I would like to be able to gracefully handle the case where the user doesn't have…
Chris Craft
- 5,285
- 6
- 46
- 63
92
votes
13 answers
How can I send and receive WebSocket messages on the server side?
How can I send and receive messages on the server side using WebSocket, as per the protocol?
Why do I get seemingly random bytes at the server when I send data from the browser to the server? It the data encoded somehow?
How does the framing work…
pimvdb
- 151,816
- 78
- 307
- 352
92
votes
6 answers
Calling protocol default implementation from regular method
I'm wondering if it's possible to achieve such a thing.
I have a Playground like this:
protocol Foo {
func testPrint()
}
extension Foo {
func testPrint() {
print("Protocol extension call")
}
}
struct Bar: Foo {
func…
cojoj
- 6,405
- 4
- 30
- 52
90
votes
9 answers
Protocol func returning Self
I have a protocol P that returns a copy of the object:
protocol P {
func copy() -> Self
}
and a class C that implements P:
class C : P {
func copy() -> Self {
return C()
}
}
However, whether I put the return value as Self I get…
aeubanks
- 1,261
- 1
- 12
- 12
89
votes
4 answers
Why I can't use let in protocol in Swift?
I have a doubt about protocols in Swift about the use of var and the keywords { get set }.
From Apple documentation:
If a protocol requires a property to be gettable and settable, that
property requirement cannot be fulfilled by a constant stored…
Massimo Polimeni
- 4,826
- 4
- 27
- 54
81
votes
7 answers
What's the difference between a protocol extended from AnyObject and a class-only protocol?
Both this declaration
protocol SomeProtocol : AnyObject {
}
and this declaration
protocol SomeProtocol : class {
}
seem to make it so that only classes can conform to this protocol (i.e. that the instances of the protocol are references to…
user102008
- 30,736
- 10
- 83
- 104
81
votes
2 answers
Can I have an init func in a protocol?
When I try to implement my protocol this way:
protocol Serialization {
func init(key keyValue: String, jsonValue: String)
}
I get an error saying: Expected identifier in function declaration.
Why am I getting this error?
Aaron Bratcher
- 6,051
- 2
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- 70
78
votes
3 answers
What is the technology behind wechat, whatsapp and other messenger apps?
I am eager to know about the architecture of different real-time messenger apps. Are they using any generic protocol/architecture?
viswas
- 1,007
- 1
- 9
- 13
76
votes
8 answers
Implementing Bittorrent Protocol
I am looking for a tutorial/blog post on how to implement bittorrent protocol step by step.
How it works? How do you make requests to peers? and talk to trackers.
I do not mind the programming language (java,ruby,perl,c#)
Hamza Yerlikaya
- 49,047
- 44
- 147
- 241
76
votes
10 answers
Swift Equatable on a protocol
I don't think this can be done but I'll ask anyway. I have a protocol:
protocol X {}
And a class:
class Y:X {}
In the rest of my code I refer to everything using the protocol X. In that code I would like to be able to do something like:
let a:X =…
drekka
- 20,957
- 14
- 79
- 135
70
votes
4 answers
How to define initializers in a protocol extension?
protocol Car {
var wheels : Int { get set}
init(wheels: Int)
}
extension Car {
init(wheels: Int) {
self.wheels = wheels
}
}
on self.wheels = wheels i get the error
Error: variable 'self' passed by reference before being…
bogen
- 9,954
- 9
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- 89
70
votes
6 answers
NSNotificationCenter vs delegation( using protocols )?
What are the pros and cons of each of them?
Where should I use them specifically?
EEE
- 4,536
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- 34
69
votes
6 answers
How to define a protocol as a type for a @ObservedObject property?
I have a swiftui view that depends on a view model, the view model has some published properties. I want define a protocol and default implementation for the view model hierarchy, and make the view dependent on the protocol not the concrete class?
I…
M.Serag
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