In one of my projects I want to use a Swift class from an Objective C class. I've created XXX-swift.h file and a bridging header file. Most swift files are working perfectly, but I found a problem of an APiResult class of mine.
#objc class ApiResult:NSObject {
var success:Bool?
var message:String?
}
and in XXX-swift.h file
SWIFT_CLASS("_TtC16RemoteController9ApiResult")
#interface ApiResult : NSObject
#property (nonatomic, copy) NSString * _Nullable message;
- (nonnull instancetype)init OBJC_DESIGNATED_INITIALIZER;
#end
there the success property is missing. A rebuild & clean build didn't work.
Why is this happening
Objective-C doesn't support optionals. The bridging from Swift to Objective-C allows optionals for class types because those just translate to nil on the ObjC side. However, Bool is a primitive type, and there's no such thing as a nil boolean value in Objective-C.
Related
I am currently trying to create my own custom iOS framework using Swift 2.3. I have a test iOS app, written in Obj-C, and it embeds + links to the custom framework.
The framework has multiple classes, two of them resembling the below:
public class Constants: NSObject
{
private static let sharedInstance = Constants()
override init() { }
public static let CONST_VALUE1 = "somevalue1"
public static let CONST_VALUE2 = "somevalue2"
}
and
public class RandomUtils: NSObject
{
private static let sharedInstance = RandomUtils()
override init() { }
public static func randomFunction(someValue: String) -> String?
{
return someValue
}
}
The RandomUtils class has no problems being seen and used in the test app. The Constants class however, cannot seem to be found, despite it being referenced to in the SDK-Swift.h header:
SWIFT_CLASS("_TtC6sdk9Constants")
#interface Constants : NSObject
+ (NSString * _Nonnull)CONST_VALUE1;
+ (NSString * _Nonnull)CONST_VALUE2;
#end
SWIFT_CLASS("_TtC6sdk16RandomUtils")
#interface RandomUtils : NSObject
+ (NSString * _Nonnull)randomFunction:(NSString * _Nonnull)someValue;
#end
In my test app, I am importing the framework umbrella header file in my ViewController's header file as such:
#import <UIKit/UIKit.h>
#import <SDK/SDK-Swift.h>
#interface TestVC : UIViewController
#property (weak, nonatomic) IBOutlet UITextField *txtValue1;
#end
Attempts to use the Constants class
NSLog(#"%#", [Constants CONST_VALUE1]);
result in this error message
Use of undeclared identifier 'Constants'
Does anyone have any idea what I could be doing wrong?
After some trial and error, I resolved the issue by placing the .framework directly into the test app folder.
I was able to see an interesting case using
Estimote nearables SDK
They have a class ESTNearable with property called zone.
// ENUM
typedef NS_ENUM(NSInteger, ESTNearableZone ) {
ESTNearableZoneUnknown = 0,
ESTNearableZoneImmediate,
ESTNearableZoneNear,
ESTNearableZoneFar,
};
// CLASS
#interface ESTNearable : NSObject <NSCopying, NSCoding>
// ...
#property (nonatomic, assign, readonly) ESTNearableZone zone;
// ...
#end
So when I try to use this method in Swift, compiler fails with that error:
As I understand there is some kind of compiler bug and for some reason it believes that I want to use old zone method from NSObject - (struct _NSZone *)zone OBJC_ARC_UNAVAILABLE; I can use other specific properties of that class without any problems.
As I use an SDK I can not change the name of the zone method. I believe I can write some kind of obj-c category, add some new method there, which will return value of original one, but I do not want to add obj-c classes in my project.
Is there any possibility to call this method from swift as I believe correct zone method will be called for class instances?
Thanks in advance!
Here I found the same question. I answered more deeply there. I could not find something more good, so I went ahead with my old assumptions.
I Added this category to Bridging Header. It worked fine.
#import <EstimoteSDK/EstimoteSDK.h>
#interface ESTNearable (Ex)
/// Solving the compiler problem that "zone" method is unavailable in Swift
#property (readonly) ESTNearableZone nearableZone;
#end
// Implementation
#implementation ESTNearable (Ex)
- (ESTNearableZone)nearableZone
{
return self.zone;
}
#end
After that I just used nearableZone method in Swift
var zone = someNearable.nearableZone
I'm implementing a protocol from an Obj-C library in a Swift class that defines two properties as:
#property (nonatomic, assign, getter = isLoading) BOOL loading;
#property (nonatomic, readonly) UIExpansionStyle expansionStyle;
Although I'm not sure how to conform to these requirements in my Swift class.
I've looked at the Obj-C examples, but I haven't gleaned any solutions from that. I've tried declaring class variables with the same name, but that hasn't worked. Any suggestions on how I would go about this?
PS, the library in question is https://github.com/OliverLetterer/SLExpandableTableView
I think you're making this harder than it needs to be. With a protocol defined like this:
#protocol MyProtocol
#property (nonatomic, assign, getter = isLoading) BOOL loading;
#property (nonatomic, readonly) UIExpansionStyle expansionStyle;
#end
the following class conforms:
class Conformer : MyProtocol {
var loading: Bool
var expansionStyle: UIExpansionStyle
init(loading: Bool, expansionStyle: UIExpansionStyle) {
self.loading = loading
self.expansionStyle = expansionStyle
}
}
Prefixing boolean getters with is is a Cocoa convention, so Swift already knows about it and doesn't require you to do anything special on the swift side.
The confusing part might be all the modifiers to the Objective C property declaration. Let's go through them one by one.
nonatomic has no equivalent in Swift, nothing to do here.
assign is automatic for value types, nothing to do here either.
getter = isLoading is a Cocoa convention which Swift understands and needs nothing from you in order to make this work.
readonly you can do this in Swift (just use the get{ } syntax) but it is not necessary. This is because you are allowed to expand on the contract made by the protocol. MyProtocol requires there be a property called expansionStyle that can be read from, it does NOT say that it must not be possible to write to that property in the type that implements the protocol, just like it doesn't say you can't have other properties/methods on that same class.
Lance's answer didn't work for me, this is how I got isLoading to conform to the protocol (Swift 2.2)
var expansionStyle: UIExpansionStyle = UIExpansionStyle(0)
var _loading: Bool = false
var loading:Bool {
#objc(isLoading) get {
return self._loading
}
set(newValue){
_loading = newValue
}
}
Having an Objective c base class:
#interface ObjcClass : NSObject {
NSString *aVariable_;
}
And a swift sub-class:
class SwiftClass : ObjcClass {
func init() {
// aVariable_ can't be accessed here. An Objective-c derived
// class has direct access to it's super's instance variables!
}
}
How do I access ObjcClass aVariable_ from within SwiftClass?
Great query. We have tried to hard to get this done. The only working solution I found
get value by using self.valueForKey("aVariable_")
set value using self.setValue("New Value", forKey: "aVariable_")
Hope that helps. Possible solution without altering super class.
I couldn't find a "proper" way to do this, but I needed badly for it to work. My solution was to create a simple getter method in my Objective C superclass, like this:
header file
#interface ObjcClass : NSObject {
NSString *myVariable;
}
- (NSString *)myVariable;
in the implementation file
- (NSString *)myVariable {
return myVariable;
}
I'd love to hear of a better way of doing it, but this at least works.
I've searched a lot for this.
Eventually I changed my code from:
#interface PrjRec : NSObject {
#public
NSString* name;
}
#end
To:
#interface PrjRec : NSObject {
}
#property NSString* name;
#end
similar to #JasonTyler solution.
Then I can access to my object property from Swift code with simple dot notation <object instance>.name,
But I needed to change all existing objective-c references from
<object instance>->name
To:
<object instance>.name
or
_name
if inside class unit.
I hope for a better solution too.
This worked as a pretty neat solution for me, just adding a Swift variable like:
var myInstanceVar: String {
return self.value(forKey: "myInstanceVar") as! String
}
If you are willing to have a property, then you can create the property to fit your needs.
#interface ObjcClass : NSObject {
NSString *aVariable_;
}
#property (nonatomic) NSString *aVariable_;
...
#implementation ObjcClass
#synthesize aVariable_ = aVariable_;
This allows the variable to be accessed as inst->aVariable_ or as inst.aVariable_. In the Objective C class the variable can be accessed as aVariable_ or self.aVariable_.
I seriously don't know why anyone does instance variables anymore (for one, they're private by default) vs properties. See Giorgio Calzolato's answer on this (apart from his last line about looking for a better solution - that IS the best solution :) ).
In my case I already had a property and was extra perplexed over why it didn't work. But I realized that the property had a custom time and it needed to be added into my SDK-Bridging-Header.h file.
So if your property is set to a custom type like this:
#property (nonatomic, weak) IBOutlet SDKMyCustomObject *customObject;
...then remember to add it to the bridging header.
i'm trying to get the Objection Framework working with Swift (XCode 6.4).
Everything works pretty well beside the macros required for register/inject objects e.g. objection_register
I followed the approach from "Bridging Cocoalumerjack with Swift" to get the macros working with Swift but XCode always complain: Use of undeclared identifier 'initialize' when implementing objectionRegister function in ObjectionSwift.m. Since i'm not to familiar with objective-c i got stuck when looking at the Objection.h initializer methods and trying to figure out whats wrong
Thx for your help!
ObjectionSwift.h
#import <Foundation/Foundation.h>
#interface ObjectionSwift : NSObject
+ (void) objectionRegister(NSString *) name;
#endif
ObjectionSwift.m
#import "ObjectionSwift.h"
#import "Objection.h"
#implementation ObjectionSwift
+ (void) objectionRegister:(NSString *) name {
objection_register_singleton(name)
}
#end
UPDATE
I switched to Typhoon as DI Framework which provides Swift support an works pretty well.
You can use class variable:
class ListingsViewController: UIViewController
{
class var initialize: Bool
{
JSObjection.registerClass(ListingsViewController.self, scope: JSObjectionScopeNormal)
return true
}
}