So I'm playing around with go-ethereum in iOS and I'm having quite a bit of trouble trying to interact with a contract deployed to Rinkeby testnet, I'm very new to the whole blockchain technology so any help is appreciated.
All I'm trying to do is access a deployed contract and get the value of a string but the issue I'm having is I get this error when I try to make a call to a bound contract:
Thread 1: Fatal error: 'try!' expression unexpectedly raised an error: Error Domain=go Code=1 "abi: cannot unmarshal string in to []interface {}" UserInfo={NSLocalizedDescription=abi: cannot unmarshal string in to []interface {}}
this is the code I'm using to make the call.
// Declare the error variables
var clientError: NSErrorPointer;
var addressError: NSErrorPointer;
var contractError: NSErrorPointer;
// Get the bindContract from Rinkeby test network.
let client = GethNewEthereumClient("https://rinkeby.infura.io/v3/398ed56d211646faaf010ca183de11f2", clientError);
let contractAddress = GethNewAddressFromHex("0x7259667715d671Ee370d7788647f95Fe7C3B532d", addressError);
guard let contractABI = ReadJsonResourceAsString(fileName: "InboxContractInterface", fileType: "json") else {
print("[ViewController] failed to read the abi json as string.")
return;
}
let boundContract = GethBindContract(contractAddress, contractABI, client, contractError);
// Prepare the callOpts
let callOpts = GethNewCallOpts();
callOpts?.setGasLimit(300000);
callOpts?.setContext(GethNewContext());
// Prepare the results & params interfaces
let results = GethNewInterfaces(1);
let params = GethNewInterfaces(0);
let stringResult = GethNewInterface();
stringResult?.setDefaultString();
try! results?.set(0, object: stringResult);
// Make the call
let methodName = "message";
try! boundContract?.call(callOpts, out_: results, method: methodName, args: params);
// Show results.
print("[ViewController] message call result: " + (stringResult?.getString())!);
And this is my contract's code:
pragma solidity ^0.4.17;
contract Inbox {
string public message;
function Inbox (string initialMessage) public {
message = initialMessage;
}
function setMessage (string newMessage) public {
message = newMessage;
}
}
For anyone that might find the same issue after digging a bit more I found this issue for android: https://github.com/ethereum/go-ethereum/issues/14832
Luckily this is already fixed, so it was totally my fault for not using the latest version.
I was using Geth v1.5.9 so after updating to v1.8.2 it finally worked, not sure which version in-between got fixed tho.
Related
I'm very new to the Kotlin Multiplatform and Swift language, I have a problem with KMM only the iOS part, I have successfully run this on Android but it fails on IOS due to concurrency issues.
Kotlin code snippet :
#Throws(Exception::class)
suspend fun getResponse(data: String): String {
var response: String
client.responsePipeline.intercept(HttpResponsePipeline.Transform) { (_, body) ->
when (context.response.status) {
HttpStatusCode.OK -> response = body as String
}
}
response = client.post(BASE_URL) {
contentType(ContentType.Application.Json)
body = data
}
return response
}
iOS code snippet :
#State var response: String = ""
Button("Click") {
Repository().getResponse(data: "hello world") { data, error in
if data != nil {
response.self = "\(data)"
}
}
}
I get HttpClient: {"output":"...","statusCode":200 } from the Api which I want but it fails anyways.
I tried wrap the post request with CoroutineScope(Dispatchers.Main){
withContext(Dispatchers.Default){}}
But no luck, any idea why?
Assuming you're on recent Kotlin and library versions, you should enable the new memory model. Put this in gradle.properties
kotlin.native.binary.memoryModel=experimental
See KaMP Kit for an example.
Migrating to Ktor 2.0.0 solved many problems for me.
I have a working REST API based on this API Gateway tutorial. I'm able to successfully invoke it via the test functionality of the AWS Console; and I'm able to successfully invoke it via my simple iOS Swift 4.2 Xcode application using the iPhone XR simulator.
I know it's working via a real, live external call because I can see the Cloudwatch logs which always register a 200 response and is sending the results back to the Client.
My problem is really in understanding the Swift code, and I'm hoping that a Swift expert can help me understand how to unpack result in the code below.
Here's my code in ViewController.swift for invoking the REST API and attempting to print result to the console:
#IBAction func userInvokeApi(_ sender: UIButton) {
print("You clicked invoke api...")
let client = SVTLambdaGateClient.default()
client.calcGet(operand2: "3", _operator: "+", operand1: "5").continueWith{ (task: AWSTask?) -> AnyObject? in
if let error = task?.error {
print("Error occurred: \(error)")
return nil
}
if let result = task?.result {
// Do something with result
print("The result is... \(result)")
}
return nil
}
}
As pointed out in the comments below, I'm getting the following result because it's printing out the address of the object:
You clicked invoke api...
The result is... <AmplifyRestApiTest.Empty: 0x600002020770> {
}
(where AmplifyRestApiTest is the name of my Xcode project.)
UPDATE When I set a breakpoint on the print statement, this is what I see in the Debug pane:
UPDATE 2
When I type task?.result there are two viable properties as per this answer from the Amplify team: error and result. So, since my API responds successfully I am assuming I just don't know how to view result.
Can someone help me understand what steps I must take to access members of this class object?
Here is the corresponding method in the API Gateway-generated iOS Swift SDK code:
/*
#param operand2
#param _operator
#param operand1
return type: Empty
*/
public func calcGet(operand2: String, _operator: String, operand1: String) -> AWSTask<Empty> {
let headerParameters = [
"Content-Type": "application/json",
"Accept": "application/json",
]
var queryParameters:[String:Any] = [:]
queryParameters["operand2"] = operand2
queryParameters["operator"] = _operator
queryParameters["operand1"] = operand1
let pathParameters:[String:Any] = [:]
return self.invokeHTTPRequest("GET", urlString: "/calc", pathParameters: pathParameters, queryParameters: queryParameters, headerParameters: headerParameters, body: nil, responseClass: Empty.self) as! AWSTask<Empty>
}
I'm fairly certain this return type of Empty refers to the Empty model defined for the REST API as shown in the screenshot below. I think it's "empty" because the API doesn't alter the response from the Lambda function back to the Client. So, it's all pass-through. Indeed, the tutorial explains that the other models -- Output and Result -- are not used because it "relies on the passthrough behavior and does not use this model."
Any thoughts?
I am attempting to pull down information from my Firebase database and use it to create an object of type Order. The error that I have printed in the catch statement is as follows.
Error Domain=myProjectName.OrderError Code=0 "(null)"
I am unsure what this means exactly, or how to fix it.
I have defined a custom error type in my Order class, as shown below.
enum OrderError: ErrorType
{
case IllegalOrderNumber
case InvalidEntry
}
The error is generated by the following code snippet.
self.ref.child("orders").observeEventType(.ChildAdded, withBlock: { (snapshot) in
let pickupLoc = snapshot.value!["pickupLocation"] as? String
let dropoffLoc = snapshot.value!["dropoffLocation"] as? String
let orderNumInt = snapshot.value!["orderNum"] as? Int
//since the database will return nil if you try and cast a string to an int
//we get it as an int then cast to string
let orderNum = String(orderNumInt)
do
{
let myOrder = try Order(PickUpLoc: pickupLoc, DropOffLoc: dropoffLoc, OrderNum: orderNum)!
self.orders.append(myOrder)
}
catch let error as NSError
{
//should never get here
print(error)
}
})
I do all of the error checking when the user enters the value into the database, so there should be no reason for there to be an error generated.
Okay, so after combing through my code I noticed two primary possible error sources. Firstly, despite the compiler not complaining, the do-catch block was not exhaustive, and therefore an additional catch was added to fix this. Secondly, I believe the error was generated by the fact that I declared my Orders array as var orders = [Order()] as opposed to var orders = [Order](), when I changed this, the program ran smoothly.
I am trying to validate different errors while downloading text files from AWS S3, and with the next piece of code:
... above here function receiving String parameters ruta, archivo, archivoLocal
let directorioURL = NSFileManager.defaultManager().URLsForDirectory(.DocumentDirectory, inDomains: .UserDomainMask).first! as NSURL
let archivoURL = directorioURL.URLByAppendingPathComponent("b\(archivoLocal)")
let downloadRequest = AWSS3TransferManagerDownloadRequest()
downloadRequest.bucket = ruta
downloadRequest.key = archivo
downloadRequest.downloadingFileURL = archivoURL
let transferManager = AWSS3TransferManager.defaultS3TransferManager()
let task = BFTask()
let executor = BFExecutor.mainThreadExecutor()
transferManager.download(downloadRequest).continueWithExecutor(executor, withBlock: { (task) -> AnyObject! in
if task.error != nil {
if task.error.domain == AWSS3TransferManagerErrorDomain {
self.processDomainErrorType(AWSS3TransferManagerErrorType(rawValue: task.error.code))
} else {
self.processError(task.error)
}
} else if task.result != nil {
do {
let mytext = try String(contentsOfURL: archivoURL, encoding: NSUTF8StringEncoding)
self.processResult(mytext)
} catch let urlerror as? NSError {
self.processError(urlerror)
}
}
...
I am getting the error:
Invalid conversion from throwing function of type '(_) throws -> AnyObject!' to non-throwing function type '#convention(block) (BFTask!) -> AnyObject!'
I obtained the "do { try } catch" syntax from https://developer.apple.com/library/prerelease/ios/documentation/Swift/Conceptual/BuildingCocoaApps/AdoptingCocoaDesignPatterns.html#//apple_ref/doc/uid/TP40014216-CH7-ID10
I can remove the error by replacing the catch clause with:
} catch _ {
self.processError(NSError(domain: "String-ContentsOfURL Error", code: 100, userInfo: nil))
}
Of course this way I will never know the real cause why ContentsOfURL could be failing.
All I can figure out why this error happens is because this syntax is valid only for OS X apps and for iOS the error handling guide at
https://developer.apple.com/library/prerelease/ios/documentation/Swift/Conceptual/Swift_Programming_Language/ErrorHandling.html#//apple_ref/doc/uid/TP40014097-CH42
allows only the second syntax unless you own the object throwing the errors from an enum structure of ErrorType type, which is not the case since I want to catch the NSError from String object, contentsOfURL function.
I hope someone could guide me through this, maybe being XCode 7 a beta, the catch syntax is still incomplete or maybe I should not matter about the reason why this function fails, but I think it is important to determine what is making this function fail and if it could be traced and fixed before reaching the do-try-catch clause.
Additionally to the above error, I am getting a warning in the task variable assignation line to BFTask() saying that "Initialization of immutable value 'task' was never used". I think this is a bug with this beta version that it doesn't include the pattern to acknowledge that the variable task is being used in the asynchronous block. I'd appreciate a lot some confirmation about this and if I just need to ignore it.
By the way, the only reason I am using XCode 7 beta is because my client wants to evaluate the app before acquiring their apple membership.
Apple replaced NSError with ErrorType in Swift 2.
Replace your own explicit usage of NSError with ErrorType and you don't get this type of compiler errors.
Hey stackoverflow members,
I work really hard on getting better on Swift, now I have a trivial problem. I'm a former C# developer so Error Handling until now was try {}... catch {}... Message... Done!
Now I'm developing an App which uses some JSON APIs. It's all working, downloading JSON Data, pack them into my Objects but there is one problem. The proper Error Handling..
I have the following code to download & parse JSON:
//Download & Parse JSON
func getJSON(urlToRequest: String) -> NSDictionary {
var url: NSURL = NSURL(string: urlToRequest)
var jsonRequest: NSURLRequest = NSURLRequest(URL: url)
var jsonResponse: AutoreleasingUnsafePointer<NSURLResponse?> = nil
var error: NSError?
var dataValue: NSData = NSURLConnection.sendSynchronousRequest(jsonRequest, returningResponse: jsonResponse, error:&error)
if error.description.isEmpty {
var jsonResult: NSDictionary = NSJSONSerialization.JSONObjectWithData(dataValue, options: NSJSONReadingOptions.MutableContainers, error: &error) as NSDictionary
if error.description.isEmpty {
return jsonResult
}
else {
return NSDictionary(object: "Error: Something with parsing went wrong :(", forKey: "error")
}
}
else {
return NSDictionary(object: "Error: There was an error with your connection :(", forKey: "error")
}
}
The error part is just temporary, the problem is my ViewController just calls one function to get the whole data for the week (days, matchups and so on)
I call it this way:
var rWrapper = RiotWrapper()
let lcsWeek: Week = rWrapper.getWeek("2014-07-07")
My getWeek method calls 3-4 functions which all parse JSON data in relation to the previous responses.
Ok, long story short question: I want to abort all Tasks if JSON or HTTP fails and fill my TableView just with an error message, how can I achieve this?
Something like: if error occurred -> Stop whatever you are doing -> return for example a null erm.. nil for week -> print error
Can someone help me? If someone have some lecture according this topic it will be fine also :D
Thanks in advance!
Btw: sorry for my "bad" english
All of your JSON parsing methods including getWeek should return a tuple with an optional return value and an error. If at any point you get an error in one of your methods from the JSON parsing, just immediately return the error with nil for the return value. Each method up the chain should check for an error from the previous methods and immediately return the error if it finds one:
func getWeek(string : String) -> (Week?, NSError) {
let (result, error) = self.otherMethod()
if error {
return (nil, error)
}
// continue happily ...
}
I would suggest having your function return an optional. It is easy to test and functions can be chained and shortcut.
func getWeek(string : String) -> Week? {
...
if error {
return nil
}
}
This can be quickly evaluated like this:
if let week = getWeek("2014-07-07") {
// handle success case
} else {
// handle nil
}
and check here for how to string together a number of functions that return optional:
https://developer.apple.com/library/prerelease/mac/documentation/Swift/Conceptual/Swift_Programming_Language/OptionalChaining.html