I am using XCode 6.1, and I have the following code snippet:
var <#InstanceFieldName#> : <#INSTANCE_FIELD_TYPE#> = <#INSTANCE_FIELD_INIT#>;
func get<#INSTANCE_FIELD_CAMEL_CASE#>() -> <#INSTANCE_FIELD_TYPE#>
{
return <#InstanceFieldName#>;
}
func set<#INSTANCE_FIELD_CAMEL_CASE#>(<#InstanceFieldName#>_param : <#INSTANCE_FIELD_TYPE#>)
{
self.<#InstanceFieldName#> = <#InstanceFieldName#>_param;
}
My issue is that I want to only have to type in the value for <#InstanceFieldName#> once, and have all 5 instances of <#InstanceFieldName#> be populated with that data. PHPStorm's Live Templates come with this functionality by default. Is there a way to make XCode's code snippets do this as well?
Related
In the Apple developer docs chapter "There and Back Again" the watch app's App is written like this:
#main
struct MyWatchApp: App {
#WKExtensionDelegateAdaptor(ExtensionDelegate.self) var extensionDelegate
#SceneBuilder var body: some Scene {
WindowGroup {
NavigationView {
ContentView()
}
}
}
}
Unfortunately I get a purple runtime warning on my var declaration that says
#WKExtensionDelegateAdaptor should only be used within an extension based process
There must be something in Xcode that explicitly defines the App structure as "extension-based" but I can't find it!
Edit: More clarification... I am trying to handle the special method that gets called after you run the HealthKit method startWatchApp(with:completion:)
The special method for watch extensions is func handle(_ workoutConfiguration: HKWorkoutConfiguration)
I cannot seem to find a way to link this function on the new App structure for watch apps.
Ok, I found it. The solution is to simply replace WKExtensionDelegate with the new WKApplicationDelegate!
You can try this solution, it is simple and universal.
import WatchKit
class ExtensionDelegate: NSObject, WKExtensionDelegate {
static var current: ExtensionDelegate? {
return (WKExtension.shared().delegate as? ExtensionDelegate)
}
...
}
Then access this current instance like below, because it is Singleton, you can access it in the entire project scope.
ExtensionDelegate.current?.dosomething()
My code:
let cgpurl = URL(string: "https://api.coingecko.com/api/v3/ping")!
let task = URLSession.shared.dataTask(with: cgpurl) { (Data, URLResponse, Error) in
if let data = Data, let string = String(data: data, encoding: .utf8) {
let CGPing = string } ; resume() }
The problem is with the 2nd use of "cgpurl". I've tried changing case to no effect. The error I'm getting is, "Cannot use instance member 'cgpurl' within property initializer; property initializers run before 'self' is available". Ok... but I can't even replace cgpurl with the actual link? Then I get the error message "Ambiguous reference to member 'dataTask(with:completionHandler:)'" I realize this release of swift was supposed to be "small" & just to "fix errors" but I've not been able to find any current documentation on this release. I'm using swift 4.2.1 with Xcode 10.1
This code was taken directly from a teaching manual for Swift 4.2
No, it wasn't. The code you have was never right, in Swift 4.2 or any other version of Swift. You have blindly copied and pasted perhaps, without looking at the overall context.
The problem is that the code, as you have it, is sitting "loose" at the top of your view controller or other class declaration, perhaps something along these lines:
class MyViewController : UIViewController {
let cgpurl = // ...
let task = // ...
}
That's wrong. The most basic rule of Swift programming is that executable code can exist only in a function. For example:
class MyViewController : UIViewController {
override func viewDidLoad() {
super.viewDidLoad()
let cgpurl = // ...
let task = // ...
}
}
That may not solve all your issues, but at least you'll get past the most basic mistake you're making and the "Cannot use instance member" compile error will go away.
I have lots of code in Swift 2.x (or even 1.x) projects that looks like this:
// Move to a background thread to do some long running work
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0)) {
let image = self.loadOrGenerateAnImage()
// Bounce back to the main thread to update the UI
dispatch_async(dispatch_get_main_queue()) {
self.imageView.image = image
}
}
Or stuff like this to delay execution:
dispatch_after(dispatch_time(DISPATCH_TIME_NOW, Int64(0.5 * Double(NSEC_PER_SEC))), dispatch_get_main_queue()) {
print("test")
}
Or any of all kinds of other uses of the Grand Central Dispatch API...
Now that I've opened my project in Xcode 8 (beta) for Swift 3, I get all kinds of errors. Some of them offer to fix my code, but not all of the fixes produce working code. What do I do about this?
Since the beginning, Swift has provided some facilities for making ObjC and C more Swifty, adding more with each version. Now, in Swift 3, the new "import as member" feature lets frameworks with certain styles of C API -- where you have a data type that works sort of like a class, and a bunch of global functions to work with it -- act more like Swift-native APIs. The data types import as Swift classes, their related global functions import as methods and properties on those classes, and some related things like sets of constants can become subtypes where appropriate.
In Xcode 8 / Swift 3 beta, Apple has applied this feature (along with a few others) to make the Dispatch framework much more Swifty. (And Core Graphics, too.) If you've been following the Swift open-source efforts, this isn't news, but now is the first time it's part of Xcode.
Your first step on moving any project to Swift 3 should be to open it in Xcode 8 and choose Edit > Convert > To Current Swift Syntax... in the menu. This will apply (with your review and approval) all of the changes at once needed for all the renamed APIs and other changes. (Often, a line of code is affected by more than one of these changes at once, so responding to error fix-its individually might not handle everything right.)
The result is that the common pattern for bouncing work to the background and back now looks like this:
// Move to a background thread to do some long running work
DispatchQueue.global(qos: .userInitiated).async {
let image = self.loadOrGenerateAnImage()
// Bounce back to the main thread to update the UI
DispatchQueue.main.async {
self.imageView.image = image
}
}
Note we're using .userInitiated instead of one of the old DISPATCH_QUEUE_PRIORITY constants. Quality of Service (QoS) specifiers were introduced in OS X 10.10 / iOS 8.0, providing a clearer way for the system to prioritize work and deprecating the old priority specifiers. See Apple's docs on background work and energy efficiency for details.
By the way, if you're keeping your own queues to organize work, the way to get one now looks like this (notice that DispatchQueueAttributes is an OptionSet, so you use collection-style literals to combine options):
class Foo {
let queue = DispatchQueue(label: "com.example.my-serial-queue",
attributes: [.serial, .qosUtility])
func doStuff() {
queue.async {
print("Hello World")
}
}
}
Using dispatch_after to do work later? That's a method on queues, too, and it takes a DispatchTime, which has operators for various numeric types so you can just add whole or fractional seconds:
DispatchQueue.main.asyncAfter(deadline: .now() + 0.5) { // in half a second...
print("Are we there yet?")
}
You can find your way around the new Dispatch API by opening its interface in Xcode 8 -- use Open Quickly to find the Dispatch module, or put a symbol (like DispatchQueue) in your Swift project/playground and command-click it, then brouse around the module from there. (You can find the Swift Dispatch API in Apple's spiffy new API Reference website and in-Xcode doc viewer, but it looks like the doc content from the C version hasn't moved into it just yet.)
See the Migration Guide for more tips.
In Xcode 8 beta 4 does not work...
Use:
DispatchQueue.main.asyncAfter(deadline: .now() + 0.5) {
print("Are we there yet?")
}
for async two ways:
DispatchQueue.main.async {
print("Async1")
}
DispatchQueue.main.async( execute: {
print("Async2")
})
This one is good example for Swift 4 about async:
DispatchQueue.global(qos: .background).async {
// Background Thread
DispatchQueue.main.async {
// Run UI Updates or call completion block
}
}
in Xcode 8 use:
DispatchQueue.global(qos: .userInitiated).async { }
Swift 5.2, 4 and later
Main and Background Queues
let main = DispatchQueue.main
let background = DispatchQueue.global()
let helper = DispatchQueue(label: "another_thread")
Working with async and sync threads!
background.async { //async tasks here }
background.sync { //sync tasks here }
Async threads will work along with the main thread.
Sync threads will block the main thread while executing.
Swift 4.1 and 5. We use queues in many places in our code. So, I created Threads class with all queues. If you don't want to use Threads class you can copy the desired queue code from class methods.
class Threads {
static let concurrentQueue = DispatchQueue(label: "AppNameConcurrentQueue", attributes: .concurrent)
static let serialQueue = DispatchQueue(label: "AppNameSerialQueue")
// Main Queue
class func performTaskInMainQueue(task: #escaping ()->()) {
DispatchQueue.main.async {
task()
}
}
// Background Queue
class func performTaskInBackground(task:#escaping () throws -> ()) {
DispatchQueue.global(qos: .background).async {
do {
try task()
} catch let error as NSError {
print("error in background thread:\(error.localizedDescription)")
}
}
}
// Concurrent Queue
class func perfromTaskInConcurrentQueue(task:#escaping () throws -> ()) {
concurrentQueue.async {
do {
try task()
} catch let error as NSError {
print("error in Concurrent Queue:\(error.localizedDescription)")
}
}
}
// Serial Queue
class func perfromTaskInSerialQueue(task:#escaping () throws -> ()) {
serialQueue.async {
do {
try task()
} catch let error as NSError {
print("error in Serial Queue:\(error.localizedDescription)")
}
}
}
// Perform task afterDelay
class func performTaskAfterDealy(_ timeInteval: TimeInterval, _ task:#escaping () -> ()) {
DispatchQueue.main.asyncAfter(deadline: (.now() + timeInteval)) {
task()
}
}
}
Example showing the use of main queue.
override func viewDidLoad() {
super.viewDidLoad()
Threads.performTaskInMainQueue {
//Update UI
}
}
I am writing an iOS App (using xcode 7.3 and swift 2.2) using JavascriptCode framework. Calling javascript methods from swift works perfect, but when I call the swift method from javascript, xcode simply shows a "loading" type of symbol and nothing happens. I need to "force quit" xcode to get out of this state.
I have followed https://www.raywenderlich.com/124075/javascriptcore-tutorial and http://nshipster.com/javascriptcore/ and I am trying pretty simple calls.
Has anyone faced this kind of issue?
My swift code is as follows:
#objc protocol WindowJSExports : JSExport {
var name: String { get set }
func getName() -> String
static func createWindowWithName(name: String) -> WindowJS
}
#objc class WindowJS : NSObject, WindowJSExports {
dynamic var name: String
init(name: String) {
self.name = name
}
class func createWindowWithName(name: String) -> WindowJS {
return WindowJS(name: name)
}
func getName() -> String {
NSLog("getName called from JS context")
return "\(name)"
}
}
I am initializing the context as follows:
runContext = JSContext()
runContext.name = "test_Context"
windowToJs = WindowJS(name: "test")
runContext.setObject(windowToJs.self, forKeyedSubscript: "WindowJS")
If I replace the last two lines in above code with below code without instantiating it, the code simply fails to load.
runContext.setObject(WindowJS.self, forKeyedSubscript: "WindowJS")
And the javascript code is as simple as
function check() {
return WindowJS.getName()
}
I do see the breakpoint being hit in the JS function check and when the WindowJS.getName gets called, xcode simply becomes unresponsive.
The setTimeout could be solved by adding following piece of code to my swift function.
let setTimeout: #convention(block) (JSValue, Int) -> () =
{ callback, timeout in
let timeVal = Int64(timeout)
dispatch_after(dispatch_time(DISPATCH_TIME_NOW, timeVal), dispatch_get_main_queue(), { callback.callWithArguments(nil)})
}
To expose this native code to the JS context, I also added following.
runContext.setObject(unsafeBitCast(setTimeout, AnyObject.self), forKeyedSubscript: "setTimeout")
Things then worked fine.
You're creating a deadlock since you are calling from Swift to JavaScript back to Swift. I'm not sure exactly why it is a deadlock but I had a similar issue with WKWebView on Mac recently.
You need to decouple this and make the communication asynchronous. This obviously means you cannot simply return a value from your JS function in this case.
To decouple, you can break the deadlock by deferring the work the JavaScript function needs to do out of the current runloop iteration using setTimeout:
function myFunction() {
setTimeout(function() {
// The actual work is done here.
// Call the Swift part here.
}, 0);
}
The whole native ↔︎ JavaScript communication is very, very tricky. Avoid it if you can. There's a project called XWebView that may be able to help you as it tries to ease bridging between the two worlds.
I'm not clear on how to use this properly but had seen other people doing this type of thing:
func application(application: UIApplication, handleEventsForBackgroundURLSession identifier: String, completionHandler: () -> Void) {
manager.sharedInstance.backgroundCompletionHandler = completionHandler
}
In our similar implementation, at this point completionHandler is partial apply forwarder for reabstraction thunk helper...
Where manager is (despite being a singleton) essentially:
let configuration = NSURLSessionConfiguration.backgroundSessionConfigurationWithIdentifier("com.ourcompany.app")
let manager = Alamofire.Manager(configuration: configuration)
However this causes the following warning to be printed in the console:
Warning: Application delegate received call to -application:handleEventsForBackgroundURLSession:completionHandler: but the completion handler was never called.
I set a breakpoint here and at this point the message is already visible in the console and backgroundCompletionHandler is nil.
We're building against the iOS 9 SDK with Xcode 7.0 and currently using Alamofire 2.0.2
I originally thought this was introduced when we merged our Swift 2.0 branch but I'm also seeing the message with an earlier commit using Xcode 6.4 against the iOS 8 SDK.
Update 1
To address #cnoon's suggestions:
The identifier matches - the configuration and manager are set inside a singleton so there's no way for it to be wrong.
When adding and printing inside of didSet on backgroundCompletionHandler in the Manager class, the message is logged before the warning.
When printing inside of the closure set to sessionDidFinishEventsForBackgroundURLSession on the delegate inside the Manager class, the message is printed after the warning.
When overriding sessionDidFinishEventsForBackgroundURLSession and printing inside of it before calling backgroundCompletionHandler, the message is printed after the warning.
As for verifying I have my Xcode project set up correctly for background sessions, I'm not sure how to do that and couldn't find any documentation on how to do so.
I should note that when trying to upload some screenshots from my phone I was initially unable to reproduce this issue in order to try these suggestions.
It was only after trying to share some photos that I was able to reproduce this again. I'm not sure or the correlation (if any) but it may be related to the photos taking longer to upload.
Update 2
The UIBackgroundModes are set exactly as #Nick described, and calling completionHandler() directly inside of application:handleEventsForBackgroundURLSession:completionHandler: does not display the warning.
Update 3
So, it appears I overlooked an small but important detail. There's a wrapper around Alamofire.Manager that doesn't expose it directly. The relevant part of its implementation looks like this:
private var manager: Manager
public var backgroundCompletionHandler: (() -> Void)? {
get {
return manager.backgroundCompletionHandler
}
set {
manager.backgroundCompletionHandler = backgroundCompletionHandler
}
}
and setting the completion handler in the AppDelegate executes that code path.
func application(application: UIApplication, handleEventsForBackgroundURLSession identifier: String, completionHandler: () -> Void) {
myManager.sharedInstance.backgroundCompletionHandler = completionHandler
}
I've confirmed that the following change to expose the instance of Alamofire.Manager and access it directly does not produce the warning:
public var manager: Manager
// public var backgroundCompletionHandler: (() -> Void)? {
// get {
// return manager.backgroundCompletionHandler
// }
// set {
// manager.backgroundCompletionHandler = backgroundCompletionHandler
// }
// }
and in the AppDelegate:
func application(application: UIApplication, handleEventsForBackgroundURLSession identifier: String, completionHandler: () -> Void) {
myManager.sharedInstance.manager.backgroundCompletionHandler = completionHandler
}
Based on this it appears that using a computed property to proxy the completion handler is the cause of the issue.
I'd really prefer not to expose this property and would love to know of any workarounds or alternatives.
It appears as though everything you are doing is correct. I have an example app that does exactly what you've described that works correctly and does not throw the warning you are seeing. I'm guessing you still have some small error somewhere. Here are a few ideas to try out:
Verify the identifier matches the identifier of your background session
Add a didSet log statement on the backgroundSessionHandler in the Manager class temporarily to verify it is getting set
Add a log statement into the sessionDidFinishEventsForBackgroundURLSession to verify it is getting called as expected
Override the sessionDidFinishEventsForBackgroundURLSession on the delegate and manually call the backgroundSessionHandler
Verify you have your Xcode project set up correctly for background sessions
Update 2
Your computed property is wrong. Instead it needs to set the backgroundCompletionHandler to newValue. Otherwise you are never setting it to the new value correctly. See this thread for more info.