How does one make protocols and their extensions in Swift store properties?How to have stored properties in Swift, the same way I had on Objective-C?Swift - Protocol extensions - Property default valuesSwift extension storage for protocolsHow to call Objective-C code from SwiftWhy no stored type properties for classes in swift?How can I make a weak protocol reference in 'pure' Swift (without @objc)Swift Beta performance: sorting arraysSwift: Generic ProtocolsMutating Function in Protocol Extension Where Self is UIViewControllerSwift - Protocol extensions - Property default valuesWhy must Protocol defaults be implemented via Extensions in Swift?Swift protocol with a member typed as another protocolWhen and why would i use Protocols in Swift?
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How does one make protocols and their extensions in Swift store properties?
How to have stored properties in Swift, the same way I had on Objective-C?Swift - Protocol extensions - Property default valuesSwift extension storage for protocolsHow to call Objective-C code from SwiftWhy no stored type properties for classes in swift?How can I make a weak protocol reference in 'pure' Swift (without @objc)Swift Beta performance: sorting arraysSwift: Generic ProtocolsMutating Function in Protocol Extension Where Self is UIViewControllerSwift - Protocol extensions - Property default valuesWhy must Protocol defaults be implemented via Extensions in Swift?Swift protocol with a member typed as another protocolWhen and why would i use Protocols in Swift?
The following is a workaround for the "problem" that protocols and their extensions in Swift do not store properties. It seems to "work" but I am wondering what reasons people might have for avoiding it?
fileprivate var strings: [String] = []
protocol SomeProat
func add(someString: String)
extension SomeProat
func add(someString: String)
strings.append(someString)
print(strings)
(I realise this question could be interpreted as subjective btw).
swift protocols protected protocol-extension
asked Mar 8 at 21:08
Joseph Beuys' MumJoseph Beuys' Mum
83311030
|
show 3 more comments
The following is a workaround for the "problem" that protocols and their extensions in Swift do not store properties. It seems to "work" but I am wondering what reasons people might have for avoiding it?
fileprivate var strings: [String] = []
protocol SomeProat
func add(someString: String)
extension SomeProat
func add(someString: String)
strings.append(someString)
print(strings)
(I realise this question could be interpreted as subjective btw).
swift protocols protected protocol-extension
asked Mar 8 at 21:08
Joseph Beuys' MumJoseph Beuys' Mum
83311030
2
stringis a global variable in your code, it is not inside your protocol
– Zich
Mar 8 at 21:11
Still interesting tho, thanks
– Joseph Beuys' Mum
Mar 8 at 21:20
1
As @Zich says,stringsis a global variable. All instances of any type adopting your protocol will share the same strings, that makes it not very useful.
– Martin R
Mar 8 at 21:23
1
Why is people answering with comments?
– TimTwoToes
Mar 8 at 21:24
2
Can you please clarify what you are asking for? The title asks how to add stored properties in an extension, a possible solution are associated object, compare e.g. stackoverflow.com/q/34933928/1187415 or stackoverflow.com/q/25426780/1187415. – Or are you asking if your workaround is correct?
– Martin R
Mar 8 at 21:31
|
show 3 more comments
The following is a workaround for the "problem" that protocols and their extensions in Swift do not store properties. It seems to "work" but I am wondering what reasons people might have for avoiding it?
fileprivate var strings: [String] = []
protocol SomeProat
func add(someString: String)
extension SomeProat
func add(someString: String)
strings.append(someString)
print(strings)
(I realise this question could be interpreted as subjective btw).
swift protocols protected protocol-extension
asked Mar 8 at 21:08
Joseph Beuys' MumJoseph Beuys' Mum
83311030
The following is a workaround for the "problem" that protocols and their extensions in Swift do not store properties. It seems to "work" but I am wondering what reasons people might have for avoiding it?
fileprivate var strings: [String] = []
protocol SomeProat
func add(someString: String)
extension SomeProat
func add(someString: String)
strings.append(someString)
print(strings)
(I realise this question could be interpreted as subjective btw).
swift protocols protected protocol-extension
swift protocols protected protocol-extension
asked Mar 8 at 21:08
Joseph Beuys' MumJoseph Beuys' Mum
83311030
asked Mar 8 at 21:08
Joseph Beuys' MumJoseph Beuys' Mum
83311030
asked Mar 8 at 21:08
Joseph Beuys' MumJoseph Beuys' Mum
83311030
asked Mar 8 at 21:08
Joseph Beuys' MumJoseph Beuys' Mum
83311030
asked Mar 8 at 21:08
Joseph Beuys' MumJoseph Beuys' Mum
83311030
83311030
2
stringis a global variable in your code, it is not inside your protocol
– Zich
Mar 8 at 21:11
Still interesting tho, thanks
– Joseph Beuys' Mum
Mar 8 at 21:20
1
As @Zich says,stringsis a global variable. All instances of any type adopting your protocol will share the same strings, that makes it not very useful.
– Martin R
Mar 8 at 21:23
1
Why is people answering with comments?
– TimTwoToes
Mar 8 at 21:24
2
Can you please clarify what you are asking for? The title asks how to add stored properties in an extension, a possible solution are associated object, compare e.g. stackoverflow.com/q/34933928/1187415 or stackoverflow.com/q/25426780/1187415. – Or are you asking if your workaround is correct?
– Martin R
Mar 8 at 21:31
|
show 3 more comments
2
stringis a global variable in your code, it is not inside your protocol
– Zich
Mar 8 at 21:11
Still interesting tho, thanks
– Joseph Beuys' Mum
Mar 8 at 21:20
1
As @Zich says,stringsis a global variable. All instances of any type adopting your protocol will share the same strings, that makes it not very useful.
– Martin R
Mar 8 at 21:23
1
Why is people answering with comments?
– TimTwoToes
Mar 8 at 21:24
2
Can you please clarify what you are asking for? The title asks how to add stored properties in an extension, a possible solution are associated object, compare e.g. stackoverflow.com/q/34933928/1187415 or stackoverflow.com/q/25426780/1187415. – Or are you asking if your workaround is correct?
– Martin R
Mar 8 at 21:31
2
2
string is a global variable in your code, it is not inside your protocol– Zich
Mar 8 at 21:11
string is a global variable in your code, it is not inside your protocol– Zich
Mar 8 at 21:11
Still interesting tho, thanks
– Joseph Beuys' Mum
Mar 8 at 21:20
Still interesting tho, thanks
– Joseph Beuys' Mum
Mar 8 at 21:20
1
1
As @Zich says,
strings is a global variable. All instances of any type adopting your protocol will share the same strings, that makes it not very useful.– Martin R
Mar 8 at 21:23
As @Zich says,
strings is a global variable. All instances of any type adopting your protocol will share the same strings, that makes it not very useful.– Martin R
Mar 8 at 21:23
1
1
Why is people answering with comments?
– TimTwoToes
Mar 8 at 21:24
Why is people answering with comments?
– TimTwoToes
Mar 8 at 21:24
2
2
Can you please clarify what you are asking for? The title asks how to add stored properties in an extension, a possible solution are associated object, compare e.g. stackoverflow.com/q/34933928/1187415 or stackoverflow.com/q/25426780/1187415. – Or are you asking if your workaround is correct?
– Martin R
Mar 8 at 21:31
Can you please clarify what you are asking for? The title asks how to add stored properties in an extension, a possible solution are associated object, compare e.g. stackoverflow.com/q/34933928/1187415 or stackoverflow.com/q/25426780/1187415. – Or are you asking if your workaround is correct?
– Martin R
Mar 8 at 21:31
|
show 3 more comments
1 Answer
1
active
oldest
votes
There is no good way to do what you're asking in pure Swift on non-Apple platforms.
If you are on an Apple platform (macOS, iOS, tvOS, watchOS), and your conforming type is a class, then you can use the associated object support provided by the Objective-C runtime:
import ObjectiveC
protocol MyProtocol: class
var strings: [String] get
func add(someString: String)
private var MyProtocolSomeStringKey: UInt8 = 0
extension MyProtocol
var strings: [String]
get
return objc_getAssociatedObject(self, &MyProtocolSomeStringKey) as? [String] ?? []
set
let value = newValue.isEmpty ? nil : newValue
objc_setAssociatedObject(self, &MyProtocolSomeStringKey, value, .OBJC_ASSOCIATION_RETAIN)
func add(someString: String)
strings.append(someString)
class MyObject
extension MyObject: MyProtocol
let myObject = MyObject()
myObject.add(someString: "hello")
myObject.add(someString: "world")
print(myObject.strings)
// Output: ["hello", "world"]
answered Mar 8 at 21:35
rob mayoffrob mayoff
296k42598647
add a comment |
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1 Answer
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active
oldest
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oldest
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active
oldest
votes
There is no good way to do what you're asking in pure Swift on non-Apple platforms.
If you are on an Apple platform (macOS, iOS, tvOS, watchOS), and your conforming type is a class, then you can use the associated object support provided by the Objective-C runtime:
import ObjectiveC
protocol MyProtocol: class
var strings: [String] get
func add(someString: String)
private var MyProtocolSomeStringKey: UInt8 = 0
extension MyProtocol
var strings: [String]
get
return objc_getAssociatedObject(self, &MyProtocolSomeStringKey) as? [String] ?? []
set
let value = newValue.isEmpty ? nil : newValue
objc_setAssociatedObject(self, &MyProtocolSomeStringKey, value, .OBJC_ASSOCIATION_RETAIN)
func add(someString: String)
strings.append(someString)
class MyObject
extension MyObject: MyProtocol
let myObject = MyObject()
myObject.add(someString: "hello")
myObject.add(someString: "world")
print(myObject.strings)
// Output: ["hello", "world"]
answered Mar 8 at 21:35
rob mayoffrob mayoff
296k42598647
add a comment |
There is no good way to do what you're asking in pure Swift on non-Apple platforms.
If you are on an Apple platform (macOS, iOS, tvOS, watchOS), and your conforming type is a class, then you can use the associated object support provided by the Objective-C runtime:
import ObjectiveC
protocol MyProtocol: class
var strings: [String] get
func add(someString: String)
private var MyProtocolSomeStringKey: UInt8 = 0
extension MyProtocol
var strings: [String]
get
return objc_getAssociatedObject(self, &MyProtocolSomeStringKey) as? [String] ?? []
set
let value = newValue.isEmpty ? nil : newValue
objc_setAssociatedObject(self, &MyProtocolSomeStringKey, value, .OBJC_ASSOCIATION_RETAIN)
func add(someString: String)
strings.append(someString)
class MyObject
extension MyObject: MyProtocol
let myObject = MyObject()
myObject.add(someString: "hello")
myObject.add(someString: "world")
print(myObject.strings)
// Output: ["hello", "world"]
answered Mar 8 at 21:35
rob mayoffrob mayoff
296k42598647
add a comment |
There is no good way to do what you're asking in pure Swift on non-Apple platforms.
If you are on an Apple platform (macOS, iOS, tvOS, watchOS), and your conforming type is a class, then you can use the associated object support provided by the Objective-C runtime:
import ObjectiveC
protocol MyProtocol: class
var strings: [String] get
func add(someString: String)
private var MyProtocolSomeStringKey: UInt8 = 0
extension MyProtocol
var strings: [String]
get
return objc_getAssociatedObject(self, &MyProtocolSomeStringKey) as? [String] ?? []
set
let value = newValue.isEmpty ? nil : newValue
objc_setAssociatedObject(self, &MyProtocolSomeStringKey, value, .OBJC_ASSOCIATION_RETAIN)
func add(someString: String)
strings.append(someString)
class MyObject
extension MyObject: MyProtocol
let myObject = MyObject()
myObject.add(someString: "hello")
myObject.add(someString: "world")
print(myObject.strings)
// Output: ["hello", "world"]
answered Mar 8 at 21:35
rob mayoffrob mayoff
296k42598647
There is no good way to do what you're asking in pure Swift on non-Apple platforms.
If you are on an Apple platform (macOS, iOS, tvOS, watchOS), and your conforming type is a class, then you can use the associated object support provided by the Objective-C runtime:
import ObjectiveC
protocol MyProtocol: class
var strings: [String] get
func add(someString: String)
private var MyProtocolSomeStringKey: UInt8 = 0
extension MyProtocol
var strings: [String]
get
return objc_getAssociatedObject(self, &MyProtocolSomeStringKey) as? [String] ?? []
set
let value = newValue.isEmpty ? nil : newValue
objc_setAssociatedObject(self, &MyProtocolSomeStringKey, value, .OBJC_ASSOCIATION_RETAIN)
func add(someString: String)
strings.append(someString)
class MyObject
extension MyObject: MyProtocol
let myObject = MyObject()
myObject.add(someString: "hello")
myObject.add(someString: "world")
print(myObject.strings)
// Output: ["hello", "world"]
answered Mar 8 at 21:35
rob mayoffrob mayoff
296k42598647
answered Mar 8 at 21:35
rob mayoffrob mayoff
296k42598647
answered Mar 8 at 21:35
rob mayoffrob mayoff
296k42598647
answered Mar 8 at 21:35
rob mayoffrob mayoff
296k42598647
296k42598647
add a comment |
add a comment |
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2
stringis a global variable in your code, it is not inside your protocol– Zich
Mar 8 at 21:11
Still interesting tho, thanks
– Joseph Beuys' Mum
Mar 8 at 21:20
1
As @Zich says,
stringsis a global variable. All instances of any type adopting your protocol will share the same strings, that makes it not very useful.– Martin R
Mar 8 at 21:23
1
Why is people answering with comments?
– TimTwoToes
Mar 8 at 21:24
2
Can you please clarify what you are asking for? The title asks how to add stored properties in an extension, a possible solution are associated object, compare e.g. stackoverflow.com/q/34933928/1187415 or stackoverflow.com/q/25426780/1187415. – Or are you asking if your workaround is correct?
– Martin R
Mar 8 at 21:31