I'm immigrating my old ObjectiveC code to swift. In ObjcC had a separate class to handle my Admob activity.
In this class I've created a pointer in the init func, and when changing scene, I could use this pointer to change the location of the ads banner.
#implementation MyAdsSupport
+(id)ShowAds:(My_Ads_Position)posIndex
{
if (_adsBannerPointer == nil)
{
_adsBannerPointer = [[KTFAdsSupport alloc]initAds:posIndex];
}
else
{
[_adsBannerPointer setAdsPosition:posIndex];
}
return _adsBannerPointer;
}
In Swift I created the Admob class, and managed to present ads on screen but when I try to call the pointer from another class it returns always nil.
Here is my Swift Code:
var adsPointer: My_Ads_Support!
func initAds(myView: UIViewController, atPos: My_Ads_Position) -> KTF_Ads_Support {
if adsPointer == nil {
adsPointer = self
adsPointer.ShowAds(myView: myView, atPos: atPos)
}
else
{
print("adsPointer ALIVE")
adsPointer.setAdsPos( atPos: atPos)
}
return self.adsPointer!
}
How can I set a pointer in Swift to be able to reach the ads banner from any scene?
In your Objective-C code you have three methods, the instance methods initAds: and setAdsPosition:, and the class method ShowAds:. The latter uses a variable, presumably declared static, called _adsBannerPointer.
Your Swift code is not the same. It has two methods, the instance methods initAds and setAdsPos, and one variable, the instance variable adsPointer.
In Swift class methods are termed type methods (as they can belong to classes, structs and enumerations) and are indicated by the use of the keyword static, type (class) variables are also indicated with static. So to follow your Objective-C model you need something along the lines of:
static var adsPointer: My_Ads_Support!
// instance init
init(startingPos : My_Ads_Position) { ... }
// instance set position
fun setAdsPos(atPos : My_Ads_Position) { ... }
static func showAds(myView: UIViewController, atPos: My_Ads_Position) -> KTF_Ads_Support { ... }
HTH
Related
I got a ListView in SwiftUI and want to generate RowViews depending on a given property.
Therefore I want to check the property of the element in the ForEach loop.
Xcode does not recognize the type of the element, thats why i want to cast the element to the correct Class which is an NSManagedObject Subclass.
I created the NSManagedObject Subclass from the xcdatamodeld (Editor -> Create NSManagedObject Subclass...).
The NSManagedObject Subclass is created in objective-c and I added the .h file to the bridging header.
I have no problem working with the NSManagedObject Subclass in the rest of the project.
I can even create an property of that Type in the same Struct like so:
struct MyListView: View {
var test : MyNSManagedObjectSubclass //Xcode does recognize it here
For some reason Xcode wont recognize the NSManagedObject Subclass inside the ForEach Loop.
code looks like:
struct MyListView: View {
var test : MyNSManagedObjectSubclass //Xcode does recognize it here
#EnvironmentObject private var fetchResultsContainer : FetchedResultsContainer
var body: some View {
NavigationView{
VStack{
ForEach(fetchResultsContainer.results , id: \.identifier) { result in
if let castedResult = result as! MyNSManagedObjectSubclass { //Xcode does not recognize it here
if castedResult.property{
ResultRowView(input: result)
}
}
}
}
}
}
}
FetchedResultsContainer:
#objc class FetchedResultsContainer : NSObject, ObservableObject{
#objc #Published var results: [MyNSManagedObjectSubclass]()
#objc static let sharedInstance: FetchedResultsContainer = {
let instance = FetchedResultsContainer()
return instance
}()
}
I feel like im missing something obvious, as im still quite new to Swift and SwiftUI.
Appreciate your help.
Ok after taking a step back and simply coding it again from scratch it simply worked an no casting was needed...
List(fetchResultsContainer.results, id: \.identifier) { result in
if (result.property == 0) {
//do something
}
}
My assumption that the casting was not working was not correct.
I probably checked result.property == false, with property being of type NSNumber and it gave out some strange compile errors that led me on the wrong path.
I am looking at the Swift code of the ThemeKit theming library.
In particular I would like to understand the following code in NSColor+ThemeKit.swift:
// ThemeKit.set() replacement to use theme-aware color
#objc public func themeKitSet() {
// call original .set() function
themeKitSet()
// check if the user provides an alternative color
if ThemeManager.shared.isEnabled && isThemeOverriden {
// call ThemeColor.set() function
ThemeColor.color(with: Selector(colorNameComponent)).set()
}
}
There is what appears to be an endless recursive call, but presumably can't be, since the code works fine. This is confirmed by setting a breakpoint on the call to themeKitSet(). It is not possible to step into the call and execution continues without recursion.
Earlier in the file there is the following call:
swizzleInstanceMethod(cls: NSClassFromString("NSDynamicSystemColor"), selector: #selector(set), withSelector: #selector(themeKitSet))
With the implementation in NSObject+ThemeKit.swift as follows:
/// Swizzle instance methods.
#objc internal class func swizzleInstanceMethod(cls: AnyClass?, selector originalSelector: Selector, withSelector swizzledSelector: Selector) {
guard cls != nil else {
print("Unable to swizzle \(originalSelector): dynamic system color override will not be available.")
return
}
// methods
let originalMethod = class_getInstanceMethod(cls, originalSelector)
let swizzledMethod = class_getInstanceMethod(cls, swizzledSelector)
// add new method
let didAddMethod = class_addMethod(cls, originalSelector, method_getImplementation(swizzledMethod!), method_getTypeEncoding(swizzledMethod!))
// switch implementations
if didAddMethod {
class_replaceMethod(cls, swizzledSelector, method_getImplementation(originalMethod!), method_getTypeEncoding(originalMethod!))
} else {
method_exchangeImplementations(originalMethod!, swizzledMethod!)
}
}
I suspect this is responsible for the magic, but my limited understanding of both Swift and Objective-C is letting me down.
What is happening here? Why is the apparently recursive call not actually recursive?
You correctly identified the magic bit: it's called method swizzling, and it's a way of wholesale replacing an existing method implementation.
You'll see this seemingly-recursive pattern a lot when method swizzling: that themeKitSet call actually runs the original implementation, as the comment says. It's because swizzling swaps the implementations of two methods, in this case themeKitSet and NSDynamicSystemColor.set.
Therefore, post-swizzle, NSDynamicSystemColor.set runs the code you see there, and themeKitSet has become the original implementation.
Say I have a class called ExampleClass.
Say I then write code like so:
#objc(ExampleClass)
class ExampleClass: NSObject {
#objc class func exampleFunc() -> Void {
}
}
With an Objective-C file header like so:
#import <Foundation/Foundation.h>
#import <React/RCTBridgeModule.h>
#interface RCT_EXTERN_MODULE(ExampleClass, NSObject)
RCT_EXTERN_METHOD(exampleFunc)
#end
Which I then consume in my React Native app like so:
console.log('exampleClass', React.NativeModules.ExampleClass);
console.log('exampleFunc', React.NativeModules.ExampleClass.exampleFunc)
The first console log results in {exampleFunc: f}
The second results in undefined,
Calling the function: React.NativeModules.ExampleClass.exampleFunc() results in an app crash with:
Exception 'exampleFunc is not a recognized Objective-C method.' was thrown while invoking setupLogger on target ExampleClass with params (
While changing only the Swift so that it reads:
#objc(ExampleClass)
class ExampleClass: NSObject {
#obj func exampleFunc() -> Void {
}
}
results in calling the function (which, yes) does nothing at present.
How can I expose class level variables? I am trying to write functional Swift, and I am using class methods to simulate structs.
I believe the problem is that RCT_EXPORT_METHOD() only works on instance methods, not class methods, according to my own similar problem and some discussion here: https://github.com/facebook/react-native/issues/2311
My use case is trying to bridge a getInstance() method for a Swift singleton class. This is problematic because when you reference NativeModules.ExampleClass from javascript, which has been exported with RCT_EXTERN_MODULE(), RN calls init() on its own, which you don't want for a singleton (init() reference: https://samwize.com/2017/02/09/calling-a-view-controller-function-from-react-native/)
The best way I've found to accomplish this is pretty ugly. I have a dummy wrapper class that does nothing except call methods on the singleton, and this is the class I export to Objective C (and therefore to React Native). It's basically like this:
#objc(StupidWrapperClass)
class StupidWrapperClass : NSObject {
#objc(pseudoSingletonSomeMethod)
public func pseudoSingletonSomeMethod() {
let singleton = ActualClass.getInstance()
singleton.someMethod()
}
}
and then in the .m bridge file:
#interface RCT_EXTERN_MODULE(StupidWrapperClass, NSObject)
RCT_EXTERN_METHOD(pseudoSingletonSomeMethod)
#end
You could do something like this for a class method, too:
#objc(StupidWrapperClass)
class StupidWrapperClass : NSObject {
#objc(pseudoClassMethod)
public func pseudoClassMethod() {
ActualClass.theRealClassMethod()
}
}
I know I'm kinda late to the party but I recently faced the same problem and I fixed it using a different approach. Adding to the answer given above by #thejoelpatrol, a different approach would be to store the object's reference created by react native in some static variable that would be accessible by you. Then we can use the variable to access the object created by react-native anytime.
Whenever React Native tries to instantiate the class, it would come to the init. inside the init, we can save the reference to the object created by RN.
#objc public class MyClass {
#objc public static var shared: MyClass?
init() {
MyClass.shared = self
}
}
The .m bridge file is as follows:
#interface RCT_EXTERN_MODULE(MyClass)
RCT_EXTERN_METHOD(myClassMethod)
#end
I'm trying to get access to MKMapSnapshotter's private instance variables _lodpiSnapshotCreator and _hidpiSnapshotCreator in Swift on macOS.
Thanks to class-dump, I know they're there (see here):
#interface MKMapSnapshotter : NSObject
{
[...]
VKMapSnapshotCreator *_lodpiSnapshotCreator;
VKMapSnapshotCreator *_hidpiSnapshotCreator;
}
but no matter what I do, I can't get ahold of them.
This is how I checked whether I could access them or not:
let snapshotter = MKMapSnapshotter(options: snapshotOptions)
let varNames = ["_lodpiSnapshotCreator", "_hidpiSnapshotCreator"]
for varName in varNames {
if let testIVar = class_getInstanceVariable(MKMapSnapshotter.self, varName) {
if let test = object_getIvar(snapshotter, testIVar) as? VKMapSnapshotCreator {
print(test)
} else {
print("Got ivar, but \(varName) is still nil (getInstanceVariable)")
}
} else {
print("\(varName) is nil (getInstanceVariable)")
}
}
Curiously, class_getInstanceVariable doesn't return nil, but object_getIvar does.
Got ivar, but _lodpiSnapshotCreator is still nil (getInstanceVariable)
Got ivar, but _hidpiSnapshotCreator is still nil (getInstanceVariable)
I'm at my wit's end here. All I can find via Google is people recommending the use of class_getInstanceVariable (which I already use) and key-value-coding (which doesn't work at all).
This must have been done before. Can anyone help me out?
Edit: So far, I have tried this:
#interface MKMapSnapshotter() {
#public VKMapSnapshotCreator *_lodpiSnapshotCreator;
#public VKMapSnapshotCreator *_hidpiSnapshotCreator;
}
#end
That compiles successfully, but when trying to use it, Swift keeps insisting that the members _lodpiSnapshotCreator and _hidpiSnapshotCreator don't exist.
Since we don't have or control the source code we can't change the variables to properties. Just tried this works for your case:
extension MKMapSnapshotter {
func getPrivateVariable() -> String? {
return value(forKey: "_lodpiSnapshotCreator") as? String
}
open override func value(forUndefinedKey key: String) -> Any? {
if key == "_lodpiSnapshotCreator" {
return nil
}
return super.value(forUndefinedKey: key)
}
}
You can find more about this here.
If this does not work then I believe that there is no way to access Objective-C instance variables from Swift. Only Objective-C properties get mapped to Swift properties.
Hope this helps!!
I am creating a swift framework. In that one class is like this as shown below.
import Foundation
#objc public class classA: NSObject {
public override init (){
super.init();
}
/**
Singleton intance is returned.
*/
public class var sharedInstance: classA {
struct Static {
static let instance = popeye();
}
return Static.instance
}
}
Now when i add this framework into a Objective c project and try to access "sharedInstance" i get this error.
Property 'sharedInstance' not found on object of type ClassA.
Fix it Replace 'sharedInstance' with 'sharedInstance'
But even if i try use Fix it, this issue isnt solved.
NOTE: This issue doesn't happen when i integrate this framework with a swift project!!!
I AM STUCK.. :(
I tried to reproduce your problem. At first the syntax highlighter in Xcode flagged the same error in Objective-C that you mentioned, but the code actually was built and ran fine.
However, there is a cleaner way of doing this. In your code you are using a computed type property, which is evaluated every time you access it! You work around this by introducing the struct Static, where you essentially do what could be done in classA itself, like this:
/**
Singleton intance is returned.
*/
public static var sharedInstance: classA = popeye()
Here we used a stored type property, which is a recommended way to implement singletons, see here:
https://developer.apple.com/library/content/documentation/Swift/Conceptual/BuildingCocoaApps/AdoptingCocoaDesignPatterns.html
And here is some documentation on different kinds of properties:
https://developer.apple.com/library/content/documentation/Swift/Conceptual/Swift_Programming_Language/Properties.html
Finally i was able to fix this with a minor change !! :)
Swift framework code
#objc class SingletonTest: NSObject {
// swiftSharedInstance is not accessible from ObjC
class var swiftSharedInstance: SingletonTest {
struct Singleton {
static let instance = SingletonTest()
}
return Singleton.instance
}
// the sharedInstance class method can be reached from ObjC
class func sharedInstance() -> SingletonTest {
return SingletonTest.swiftSharedInstance
}
// Some testing
func testTheSingleton() -> String {
return "Hello World"
}
}
Objective C parent project code
SingletonTest *aTest = [SingletonTest sharedInstance];
NSLog(#"Singleton says: %#", [aTest testTheSingleton]);