This is my Swift class :
class MyClass : NSObject {
public var inAppMessagesController: MPInAppMessagesController!
fun myFunction() {
self.inAppMessagesController.inAppInteractionDelegate = self // Error in this line - Cannot assign value of type 'MyClass' to type 'MPInAppMessageControllerDelegate?'
}
}
extension MyClass : MPInAppMessageControllerDelegate {
// Functions
}
As stated in comments, this is the error -
Cannot assign value of type 'MyClass' to type
'MPInAppMessageControllerDelegate?'
inAppInteractionDelegate in Objective-C class MPInAppMessagesController :
#interface MPInAppMessagesController : NSObject
#property (nonatomic, weak, nullable) id <MPInAppMessageControllerDelegate> inAppInteractionDelegate;
#end
MPInAppMessageControllerDelegate declared in MPInAppMessagesController.h :
#protocol MPInAppMessageControllerDelegate<NSObject>
// Functions
#end
The only missing part is you need to include this class inside the bridging file
#import "MPInAppMessagesController.h"
Look here to a SwiftObjc
Related
Given that there is an ObjC compatible enum written in Swift:
// from MessageType.swift
#objc enum MessageType: Int {
case one
case two
}
and an ObjC class with a property of type MessageType which has to be forwardly declared:
// from Message.h
typedef NS_ENUM(NSInteger, MessageType);
#interface Message: NSObject
#property (nonatomic, readonly) MessageType messageType;
#end
In order to use the Messagein the rest of the Swift codebase, the Message.h was added into the bridging header:
// from App-Bridging-Header.h
#import "Message.h"
Now, imagine there is a Swift class that tries to read the messageType property:
// from MessageTypeReader.swift
class MessageTypeReader {
static func readMessageType(of message: Message) -> MessageType {
return message.messageType
}
}
The compilation would fail with the following error:
Value of type 'Message' has no member 'messageType'
My question would be: Is there a way to forwardly declare a Swift enum in order for the MessageTypeReader to be able to access the property?
Note: I am aware of the possibility of rewriting the Message into Swift or importing App-Bridging-Header.h into Message.h, but that is not an option here, I am looking for a solution that would work with the current setup.
I guess one reason to use NS_ENUM on Objective-C side is to have compile time checks whether the switch statement usages are exhaustive.
If that's the case one could utilize C unions.
Objective-C Header
typedef NS_ENUM(NSInteger, MessageType);
union MessageTypeU {
MessageType objc;
NSInteger swift;
};
#interface Message : NSObject
#property (nonatomic, readonly) union MessageTypeU messageType;
#end
So the basic idea is:
Swift imports C unions as Swift structures. Although Swift doesn’t support natively declared unions, a C union imported as a Swift structure still behaves like a C union.
...
Because unions in C use the same base memory address for all of their fields, all of the computed properties in a union imported by Swift use the same underlying memory. As a result, changing the value of a property on an instance of the imported structure changes the value of all other properties defined by that structure.
see here: https://developer.apple.com/documentation/swift/imported_c_and_objective-c_apis/using_imported_c_structs_and_unions_in_swift
Objective-C Implementation Example
#interface Message ()
#property (nonatomic, readwrite) union MessageTypeU messageType;
#end
#implementation Message
- (instancetype)init
{
self = [super init];
if (self) {
_messageType.objc = MessageTypeTwo;
[self testExhaustiveCompilerCheck];
}
return self;
}
- (void)testExhaustiveCompilerCheck {
switch(self.messageType.objc) {
case MessageTypeOne:
NSLog(#"messageType.objc: one");
break;
case MessageTypeTwo:
NSLog(#"messageType.objc: two");
break;
}
}
#end
Usage on Swift Side
Since the messageType.swift property comes originally from the Swift side (see definition of MessageType) we can safely use force-unwrap.
class MessageTypeReader {
static func readMessageType(of message: Message) -> MessageType {
return MessageType(rawValue: message.messageType.swift)!
}
}
Here is a workaround suggested by Cristik (all credit goes to them):
In Message.h, declare messageType as NSInteger :
#interface Message : NSObject
#property (nonatomic, readonly) NSInteger messageType;
#end
Using NS_REFINED_FOR_SWIFT is recommended by Apple, but not necessary here.
In Swift, add the following Message extension :
extension Message {
var messageType: MessageType {
guard let type = MessageType(rawValue: self.__messageType) else {
fatalError("Wrong type")
}
return type
}
}
I develop an app that using CommonCrypto library. The problem is I can create an instance in Swift file. My object created using Objective- C. It seems can't create bridging header very well.
Error message
/Users/MNurdin/Documents/iOS/xxxxx/Models/Main.swift:15:9: 'CustomObject' does not have a member named 'encrypt'
CustomObject.h
#import <Foundation/Foundation.h>
#import <CommonCrypto/CommonCrypto.h>
#import "GTMBase64.h"
#interface CustomObject : NSObject
+ (NSString*)encrypt:(NSString*)plainText withKey:(NSString*)key;
#end
CustomObject.m
#import "CustomObject.h"
#implementation CustomObject
+ (NSString*)encrypt:(NSString*)plainText withKey:(NSString*)key{
/*--*/
return result;
}
#end
Global.swift
var instanceOfCustomObject: CustomObject = CustomObject()
println(instanceOfCustomObject.encrypt("p#$$w0rd","12345678"))
The initial + in the declaration indicates that
+ (NSString*)encrypt:(NSString*)plainText withKey:(NSString*)key;
is a class method in Objective-C. You have to call it on the
class (or type in Swift linguage) itself, not on an instance:
let encrypted = CustomObject.encrypt("p#$$w0rd", withKey: "12345678")
I have to translate the following lines of Objective-c code into swift. This is a sample from the Objective-c JSONModel-Framework where the Optional protocol provided by the Framework is applied to an instance variable of type NSString. I found a related post but i didn't managed to achieve it. With my MYModel.swift implementation Xcode complains Cannot specialize non-generic type NSString
thx for your help!
MYModel.swift
#objc(MYModel) public class MYModel : JSONModel {
...
public var name : NSString<Optional>
...
}
MYModel.h
#interface MYModel : JSONModel
...
#property (strong, nonatomic) NSString<Optional>* name;
...
JSONModel.h
...
/**
* Protocol for defining optional properties in a JSON Model class. Use like below to define
* model properties that are not required to have values in the JSON input:
*
* #property (strong, nonatomic) NSString<Optional>* propertyName;
*
*/
#protocol Optional
#end
...
The < and > are not for conforms to protocol. It is for Types with generics like Array:
Array<T>
so you can write var a: Array<String>.
You want something else, a variable should be a Type String and conform to the protocol
You can extend String with the protocol and add the needed functions yourself.
Since your Optional protocol is empty, it is enough to write:
extension NSString: Optional {} // you can use String if you like
To create the protocol write in Swift:
protocol Optional {}
You can Objective-C create the protocol, too.
You should not use Optional, because there is already one, but because Swift has namespacing, it works.
You could of course write something like that:
extension NSString: JsonOptProtocol {}
protocol JsonOptProtocol {} // or create that in Objective-C like you did
Documentation link.
Optional is a type declared in the standard library of Swift, at the moment JSONModel is not compatible with Swift because of this.
When I assign value to age, I get this error:
#interface Person : NSObject
{
int age;
}
-(void)setAge;
#end
I tried to use self.age, yet it did not work
Here is my .m file:
#implementation Person
-(void)setAge(int)value
{
age = value;
}
#end
I tried several differnet things. ..I get this error when I type this: age = value; do you know why this is?
You should add:
-(void)setAge:(int)value;
In the header file because the current method specification you have there doesn't have a parameter.
Your method in the implementation should also have the same spec as it's missing a colon currently.
You have actually declared one method (-setAge) and implemented another (-setAge:, note the colon). You should really declare age as a property and avoid explicit ivars as much as possible. Also, I hope you have properly formatted the class in your real code.
#interface Person : NSObject
#property (nonatomic) int age;
#end
#implementation Person
-(void)setAge:(int)value
{
_age = value;
}
#end
Note that it is no longer necessary to explicitly #synthesize properties, and they automatically synthesize with an underscored ivar.
I am a newbie on Monotouch. Recently, I am working on a Monotouch binding project that binds a custom iOS framework that developed myself into a .NET framework library. I follow the instructions on Xamarin but currently I am having an issue that cannot be resolved. This is my code.
**HEADER FILE IN OBJECTIVE C**
*GRG.h*
#interface GRG: NSObject {}
// Shared instance
+ (GRG*) sharedG;
// Preference class
#property (nonatomic, readonly) GRGPreferences *preferences;
// Driver version
#property (readonly,copy) NSString* driverVersion;
// More parameters...
#end
*GRGPreferences.h*
#interface GRGPreferences : NSObject <GRGPreferencesProtocol>{}
// Enable DEBUG
#property BOOL debugEnabled;
// More parameters...
#end
*GRGPreferencesProtocol.h*
#protocol GRGPreferencesProtocol <NSObject>
// More parameters...
#end
I convert my header file into this
**API DEFINITION**
[BaseType (typeof (NSObject))]
interface GRG
{
[Static][Export("sharedG")]
GRG SharedG{ get; }
[Export("preferences")]
GRGPreferences Preferences{ get;}
[Export("driverVersion", ArgumentSemantic.Copy)]
string DriverVersion {get;}
}
[BaseType (typeof (GRGPreferencesProtocol))]
public interface GRGPreferences
{
[Export("debugEnabled")]
bool DebugEnabled{ get; set;}
}
[BaseType(typeof (NSObject))]
[Model]
public interface GRGPreferencesProtocol
{}
After that, I created a test app on mono to test the newly created library and get access to the values I created. However, I got an error.
Console.WriteLine(GRG.sharedG.DriverVersion);
- This works fine. It returns the proper value.
GRGPreferences pref = GRG.SharedG.Preferences;
- Error : "Cannot cast from source type to destination type."
Console.WriteLine(GRG.sharedG.Preferences.DebugEnabled);
- Error : "Cannot cast from source type to destination type."
Can anyone please help me?
From a quick look I think this is what you want:
[BaseType (typeof (NSObject))]
public interface GRGPreferences : GRGPreferencesProtocol {
Your GRGPreferences type inherits from NSObject while implementing the protocol you want.