I have a project that is a cross of Swift and Objective-C using a bridging-header.
In my main ViewController.swift file, outside of the class declaration, I have this code:
var mainView = ViewController()
In other views that I segue to, I can use this to call a function to run back on the main ViewController by using mainView.runFunction()
How can I call this function in an Objective-C .m implementation file?
Thanks!
First of all for using swift in objective-c you need to import TargetName-Swift.h. Note that it's the target name.
For more information look at this.
You can achieve what you want in this way:
ViewController *mainView = [[UIViewController alloc] init];
[mainView runFunction];
Also you should declare your runFunction with #objc to use it in objective-c like below:
#objc func runFunction {
// what you want to do ...
}
Follow this apple article and done : Load Swift in Objective-C.
Or I already did is a "trick" using "#objc" key, look at this little explanation: What is #objc attribute, one easy way is just create a helper function that will be visible to your Objective-c class and done like:
#objc func retrieveMainView() -> UIViewController { return MyViewController() }
And you call this from your objective-c class, maybe you need to anotate your swift class with #objc, look at this two reference and you will get the idea and figure out for sure .
In your Objective file i.e. .m file add below import statement:
import "<ProjectName>-Swift.h"
For example your project name is MyProject, so import statement would look like:
import "MyProject-Swift.h"
And call your function like: [mainView runFunction];
I hope this will help. You can also refer one of my answer:
How can I import Swift code to Objective-C?
Related
I am trying to make use of an Objective-C API in Swift. I can only seem to call the shareMyInstance() method from Swift, and not the initOpenApi() method for some reason. I'm not sure if there is some sort of scope identifier present in the interface, but I can't make use of initOpenApi, even though both are in the header. I also cannot see the method bodies, but I don't believe that affects the scope of the function.
This is locking me into using Objective-C, because for some reason I can access all of the functions from Objective-C, but only 3 of the 4 from Swift.
Header file (LCOpenSDK_Api.h):
#ifndef LCOpenSDK_LCOpenSDK_Api_h
#define LCOpenSDK_LCOpenSDK_Api_h
#import <Foundation/Foundation.h>
#interface LCOpenSDK_Api: NSObject
+ (LCOpenSDK_Api*) shareMyInstance;
- (id) initOpenApi:(NSString*)addr port:(NSInteger)port CA_PATH:(NSString*)caPath;
- (NSInteger)request:(void*)req resp:(void*)resp timeout:(NSInteger)timeout;
- (void)uninitOpenApi;
#end
#endif
My code (.swift):
import Foundation
#objc(LeChangePlayerView)
class LeChangePlayerView: UIView {
//...
#objc
override init(frame: CGRect) {
super.init(frame: frame)
var lc = LCOpenSDK_Api.shareMyInstance()!; //Fine
//Need this function!
lc.initOpenApi("openapi.easy4ip.com", 443, "") //Value of type 'LCOpenSDK_Api' has no member 'initOpenApi'
}
The only possible other explanation is that there is a different header file with the same name, but different interface, but this is highly unlikely because shareMyInstance, request and unitOpenApi are all available, and going to the definition from within the swift file using Xcode points to the same file. It is a dynamic framework, and as of right now, I can only view the headers, not the method implementations. I'm not sure if there's a solution to this, but this is another problem I could use help with. Could they have locked the original source code somehow, as well as made that specific method private?
Although initOpenApi is an instance method, Swift recognises it as an initialiser as it starts with the word init. Initialisers are translated from Objective-C into Swift-style initialisers.
In Objective-C you would say something like [[LCOpenSDK_Api alloc] initOpenAPI:#"openapi.easy4ip.com", port: 443, CA_PATH: #""]
In Swift the word init is stripped and there is no need to explicitly allocate a new instance:
let lc = LC_OpenSDK_Api(openApi:"openapi.easy4ip.com:, port: 443, CA_PATH:"")
However, you need to refer to the documentation from the framework to determine if you want to access the singleton instance LC_OpenSDK_Api.shareMyInstance or whether you want to create a specific instance as I showed above.
Anyone faced problems in {Module_name}-Swift.h file for Swift 4 projects? I've noticed -Swift.h autogenerated file not working well with Swift 4 syntax unlike Swift 3.2!.
For example, -Swift.h file doesn't contain all variables and methods which implemented in the custom Swift classes which inherited from NSObject class!
I've used #objc and #classkeywords but no way.
I don't get any errors! the problem is if I've created a class like this:
import Foundation
class Utils: NSObject {
let abc: String?
func xyz() {
print("")
}
}
and navigate to {Module_name}-Swift.h I see something like that:
SWIFT_CLASS("_TtC3{Module_name}5Utils")
#interface Utils : NSObject
- (nonnull instancetype)init OBJC_DESIGNATED_INITIALIZER;
#end
Problem
Both let abc: String? and func xyz() have been never included in {Modue_name}-Swift.hfile!
I think in Swift 4 you have to mark a lot more things #objc (nothing implicit anymore) but other than that it should just be in there.
You can all check it to confirm class name in .h file like:
#class filename;
The generated file {Module}-Swift.h does not contain your variables and methods, the file is generated to give you access to the Module namespace.
The actual interface for the generated module lives in Module.swiftmodule/arm64.swiftmodule (depending on built architecture).
More information on its contents:
https://bugs.swift.org/browse/SR-2502
https://lists.swift.org/pipermail/swift-users/Week-of-Mon-20160111/000827.html
https://stackoverflow.com/a/24396175/1755720
however... the format is not documented anywhere and is subject to change. A good starting point would be to look in include/swift/Serialization/ModuleFormat.h
As to why it's not working - Swift 4 has a migration process, please ensure you have followed it: https://swift.org/migration-guide-swift4/
Xcode will pick up most things ... but it won't get everything!
And why do you need header files for Swift classes? You just can mark swift class as #objc and you will be able to reach all its properties.
I am trying to implement the following method in swift:
From the class FLIROneSDKImageReceiverDelegate, which is subclassed inside my ViewController class as so:
class ViewController: UIViewController, FLIROneSDKImageReceiverDelegate,
FLIROneSDKStreamManagerDelegate,
FLIROneSDKImageEditorDelegate{
Note that I have already created a bridging header etc.
In the FLIROneSDKImageReceiverDelegate header file:
- (void) FLIROneSDKDelegateManager:(FLIROneSDKDelegateManager *)delegateManager didReceiveBlendedMSXRGBA8888Image:(NSData *)msxImage imageSize:(CGSize)size;
Am I wrong in thinking that this is the correct way to implement this function?
func FLIROneSDKDelegateManagerdidReceiveBlendedMSXRGBA8888ImageimageSize(delegateManager: FLIROneSDKDelegateManager!, msxImage: NSData, size: CGSize){
Note that FLIROneSDKDelegateManager is a class.
Off the top of my head, but try this:
func FLIROneSDKDelegateManager(delegateManager: FLIROneSDKDelegateManager!, didReceiveBlendedMSXRGBA8888Image msxImage: NSData!, imageSize size: CGSize) {
// method imp
}
#Laxsnor's solution in the comments on the answer by #aaron-wojnowski helped me too, thanks both.
To consolidate:
The problem is a conflict created by the name FLIROneSDKDelegateManager being used as a both a class name and a function name - which seems to be OK in Objective-C but not in Swift.
Replacing the class FLIROneSDKDelegateManager with NSObject in the function parameter seems to solve the problem without side-effects. This has to be done in both the Objective-C protocol header file and the Swift delegate class source file.
NOTE I also found this same solution applied more broadly to Swift-ify the entire FLIROneSDK at https://github.com/jruhym/flirmebaby.
Happy developing for FLIROne on Swift. (I'm new to FLIROne and relatively new to Swift so apologies if my language isn't quite precise enough.)
I have a swift file "SomeController.swift" it is like this:
import Foundation
func performSomeStuff() {
println("Performing stuff")
}
Now in the app delegate, I am trying to do this: (note that the swift bridging header is imported)
[SomeController performSomeStuff]
But its not working.
I have also tried this:
import Foundation
class SomeController:NSObject {
class func performSomeStuff() {
println("Performing stuff")
}
}
But it still fails.
What is the correct way?
Add:
#objc
before the class keyword in your swift code so it will be:
#objc class SomeStuff: NSObject {
}
Also add #obj in front of any function that you want to call.
Then in your app delegate make sure to use #import "projectName-Swift.h"
Are you able to access "SomeController" class in objective-c, if not then you firstly need to add "${ProjectName}-Swift.h file and add Swift compilation support in Build settings as:
And for accessing methods from Swift to Objective-C, add
import Foundation
class SomeStuff:NSObject {
#objc class func performSomeStuff() {
println("Performing stuff")
}
}
before functions name.
In some cases, you need finer grained control over how your Swift API is exposed to Objective-C. You can use the #objc attribute if your Swift class doesn’t inherit from an Objective-C class, or if you want to change the name of a symbol in your interface as it’s exposed to Objective-C code.
https://developer.apple.com/library/prerelease/ios/documentation/Swift/Conceptual/BuildingCocoaApps/InteractingWithObjective-CAPIs.html
Ok, So I figured it out. First, here's the correct way. Its like some of you said:
In the swift file, I have it like this:
class MyController:NSObject{
class func performTask {
// Here my task is running.
}
}
Then in the app delegate, I just import the swift header file. And do this:
[MyController performTask];
Now for the part I had wrong. It was an error on my part, but maybe it'll be useful to someone else out there.
When I first created the first swift file, I had placed it inside a folder within the my Source folder. But when I started having multiple swift files, I moved the bridging header outside that folder and into the main Source folder (just for organising).
The problem was, it did not give me a direct error to tell me what was the problem. I had to check the issue navigator to identify the problem.
Hope this helps someone out there.
So I have been making an app, and everything has been working great. But today I made a new class like usual and for some reason in this class I can't access Public/Global variable from other classes. All the other classes can, but now when ever I try to make a new class I can't. How would this be fixed?
I am using Swift and Xcode 6.
Working Class:
import UIKit
import Foundation
import Parse
import CoreData
var signedIn = true
class ViewController: UIViewController {
New Class:
import UIKit
class NewClass: UIViewController {
override func viewDidLoad() {
super.viewDidLoad()
signedIn = false
}
But on signedIn = false
I get the error:
use of unresolved identifier "signedIn"
One possible issue is that your new class has a different Target or different Targets from the other one.
For example, it might have a testing target while the other one doesn't. For this specific case, you have to include all of your classes in the testing target or none of them.
Once I had this problem after renaming a file. I renamed the file from within Xcode, but afterwards Xcode couldn't find the function in the file. Even a clean rebuild didn't fix the problem, but closing and then re-opening the project got the build to work.
'Use of Unresolved Identifier' in Swift my also happen when you forgot to import a library. For example I have the error:
In which I forgot the UIKit
import UIKit
Sometimes the compiler gets confused about the syntax in your class. This happens a lot if you paste in source from somewhere else.
Try reducing the "unresolved" source file down to the bare minimum, cleaning and building. Once it builds successfully add all the complexity back to your class.
This has made it go away for me when re-starting Xcode did not work.
Another place I've seen this error is when your project has multiple targets AND multiple bridging headers. If it's a shared class, make sure you add the resource to all bridging headers.
A good tip to is to look in the left Issue Navigator panel; the root object will show the target that is issuing the complaint.
For me this error happened because I was trying to call a nested function. Only thing I had to do to have it fixed was to bring the function out to a scope where it was visible.
In my case, I had an Object-C file which was also in the same Target Membership. I fixed by adding #import "YourObjectCFileHeader.h" inside file Bridging-Header.h
Because you haven't declared it. If you want to use a variable of another class you must use
override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
var DestViewController : ViewController = segue.destinationViewController as ViewController
DestViewController.signedIn = false
}
You have to put this code at the end of the NewClass code
Your NewClass inherits from UIViewController. You declared signedIn in ViewController. If you want NewClass to be able to identify that variable it will have to be declared in a class that your NewClass inherits from.
I got this error for Mantle Framework in my Objective-Swift Project.
What i tried is ,
Check if import is there in Bridging-Header.h file
Change the Target Membership for Framework in Mantle.h file as shown in below screenshot.
Toggle between Private Membership first build the project , end up with errors.
Then build the project with Public Membership for all the frameworks appeared for Mantle.h file, you must get success.
It is just a bug of building with multiple framework in Objective-C Swift project.
If this is regarding a class you created, be sure that the class is not nested.
F.e
A.swift
class A {
class ARelated {
}
}
calling var b = ARelated() will give 'Use of unresolved identifier: ARelated'.
You can either:
1) separate the classes if wanted on the same file:
A.swift
class A {
}
class ARelated {
}
2) Maintain your same structure and use the enclosing class to get to the subclass:
var b = A.ARelated
I did a stupid mistake. I forgot to mention the class as public or open while updating code in cocoapod workspace.
Please do check whether accesor if working in separate workspace.
You forgot to declare the variable. Just put var in front of signedIn = false
My issue was calling my program with the same name as one of its cocoapods. It caused a conflict. Solution: Create a program different name.
This is not directly to your code sample, but in general about the error. I'm writing it here, because Google directs this error to this question, so it may be useful for the other devs.
Another use case when you can receive such error is when you're adding a selector to method in another class, eg:
private class MockTextFieldTarget {
private(set) var didCallDoneAction = false
#objc func doneActionHandler() {
didCallDoneAction = true
}
}
And then in another class:
final class UITextFieldTests: XCTestCase {
func testDummyCode() {
let mockTarget = MockTextFieldTarget()
UIBarButtonItem(barButtonSystemItem: .cancel, target: mockTarget, action: MockTextFieldTarget.doneActionHandler)
// ... do something ...
}
}
If in the last line you'd simply call #selector(cancelActionHandler) instead of #selector(MockTextFieldTarget.cancelActionHandler), you'd get
use of unresolved identifier
error.