I have written the following method that returns a block that I've written in Objective-C. No matter how many times I mess with the syntax I can't get a swift version of this method that the compiler likes.
- (TWCInviteAcceptanceBlock)acceptHandler
{
return ^(TWCConversation * _Nullable conversation, NSError * _Nullable error) {
if (conversation) {
NSLog("Yay")
}
else {
NSLog(#"Boo")
}
};
}
Any ideas?
Off the top of my head:
func acceptHandler() -> TWCInviteAcceptanceBlock {
return { (conversation: TWCConversation?, error: NSError?) in
if let conversation = conversation {
print("Yay")
} else {
print("Boo")
}
}
}
Related
I read somewhere here that CKError is not available in Objective-C, and I concur. For instance, this extension is available in Swift.
#available(OSX 10.10, iOS 8.0, watchOS 3.0, *)
extension CKError {
/// Retrieve partial error results associated by item ID.
public var partialErrorsByItemID: [AnyHashable : Error]? { get }
/// The original CKRecord object that you used as the basis for
/// making your changes.
public var ancestorRecord: CKRecord? { get }
/// The CKRecord object that was found on the server. Use this
/// record as the basis for merging your changes.
public var serverRecord: CKRecord? { get }
/// The CKRecord object that you tried to save. This record is based
/// on the record in the CKRecordChangedErrorAncestorRecordKey key
/// but contains the additional changes you made.
public var clientRecord: CKRecord? { get }
/// The number of seconds after which you may retry a request. This
/// key may be included in an error of type
/// `CKErrorServiceUnavailable` or `CKErrorRequestRateLimited`.
public var retryAfterSeconds: Double? { get }
}
The problem is that I need these objects in my Objective-C project.
I've somehow (I believe) managed to get the partialErrorsByItemID in Objective-C by making a category for NSError and a little comprehension of the documentation of CKError.h, like so:
CKErrorCode ckErrorCode = (CKErrorCode) _code;
if (ckErrorCode == CKErrorPartialFailure) {
// When a CKErrorPartialFailure happens this key will be set in the error's userInfo dictionary.
// The value of this key will be a dictionary, and the values will be errors for individual items with the keys being the item IDs that failed.
NSDictionary *dicError = _userInfo;
if ([dicError objectForKey:CKPartialErrorsByItemIDKey] != nil) {
NSDictionary *dic = (NSDictionary *)[dicError objectForKey:CKPartialErrorsByItemIDKey];
for (NSString* key in dic) {
NSError *newError = dic[key];
if (code == newError.code) {
match = YES;
}
}
} else {
return NO;
}
}
But again, my problem is how to get the objects serverRecord and the clientRecord. Any idea?
Here's an Objective-C category that replicates most of the CKError structure of Swift. I didn't add errorCode, localizedDescription or errorUserInfo since NSError already provides those as code, localizedDescription, and userInfo.
CloudKitExtensions.h
#import <CloudKit/CloudKit.h>
NS_ASSUME_NONNULL_BEGIN
extern const double UnknownRetrySeconds;
#interface NSError (CKError)
- (NSDictionary<id, NSError *> * _Nullable)partialErrorsByItemID;
- (CKRecord * _Nullable)ancestorRecord;
- (CKRecord * _Nullable)clientRecord;
- (CKRecord * _Nullable)serverRecord;
- (double)retryAfterSeconds; // returns UnknownRetrySeconds if not available
#end
NS_ASSUME_NONNULL_END
CloudKitExtensions.m
#import "CloudKitExtensions.h"
const double UnknownRetrySeconds = -1;
#implementation NSError (CKError)
- (NSDictionary<id, NSError *> * _Nullable)partialErrorsByItemID {
if ([self.domain isEqualToString:CKErrorDomain] && self.code == CKErrorPartialFailure) {
return self.userInfo[CKPartialErrorsByItemIDKey];
} else {
return nil;
}
}
- (CKRecord * _Nullable)ancestorRecord {
if ([self.domain isEqualToString:CKErrorDomain] && self.code == CKErrorServerRecordChanged) {
return self.userInfo[CKRecordChangedErrorAncestorRecordKey];
} else {
return nil;
}
}
- (CKRecord * _Nullable)clientRecord {
if ([self.domain isEqualToString:CKErrorDomain] && self.code == CKErrorServerRecordChanged) {
return self.userInfo[CKRecordChangedErrorClientRecordKey];
} else {
return nil;
}
}
- (CKRecord * _Nullable)serverRecord {
if ([self.domain isEqualToString:CKErrorDomain] && self.code == CKErrorServerRecordChanged) {
return self.userInfo[CKRecordChangedErrorServerRecordKey];
} else {
return nil;
}
}
- (double)retryAfterSeconds {
if ([self.domain isEqualToString:CKErrorDomain]) {
NSNumber *delayVal = self.userInfo[CKErrorRetryAfterKey];
return delayVal ? [delayVal doubleValue] : UnknownRetrySeconds;
} else {
return UnknownRetrySeconds;
}
}
#end
I completed all step of Creative SDK Image component .But,how can i convert this block into Swift language..
id<AdobeImageEditorRender> render = [photoEditor enqueueHighResolutionRenderWithImage:highResImage
completion:^(UIImage *result, NSError *error) {
if (result) {
} else {
}
}];
// Provide a block to receive updates about the status of the render
[render setProgressHandler:^(CGFloat progress) {
print("Do something")
}];
It may not be exactly this, since I don't have the SDK installed, but it should be very close to this:
let render = photoEditor.enqueueHighResolutionRenderWithImage(image) { result, error in
if let result = result {
// do something with result.
} else {
// do something with error.
}
}
render.progressHandler = { progress in
// update progress, if
}
if you reference self in the blocks, you need to put [unowned self] after the brace like this:
render.progressHandler = { [unowned self] progress in
self.updateProgress(progress)
}
I am using PromiseKit and would like to force sequential download of JSONs. The count of JSONs might change.
I have read this about chaining.
If I had a fixed number of say 3 downloads, this would be fine.
But what if I had a changing count of download that I would like to download sequentially?
This is my code for 2 URLs. I wonder how I could do this with dateUrlArray[i] iteration over the array?
- (void)downloadJSONWithPromiseKitDateArray:(NSMutableArray *)dateUrlArray {
[self.operationManager GET:dateUrlArray[0]
parameters:nil]
.then(^(id responseObject, AFHTTPRequestOperation *operation) {
NSDictionary *resultDictionary = (NSDictionary *) responseObject;
Menu *menu = [JsonMapper mapMenuFromDictionary:resultDictionary];
if (menu) {
[[DataAccess instance] addMenuToRealm:menu];
}
return [self.operationManager GET:dateUrlArray[1]
parameters:nil];
}).then(^(id responseObject, AFHTTPRequestOperation *operation) {
NSDictionary *resultDictionary = (NSDictionary *) responseObject;
Menu *menu = [JsonMapper mapMenuFromDictionary:resultDictionary];
if (menu) {
[[DataAccess instance] addMenuToRealm:menu];
}
})
.catch(^(NSError *error) {
dispatch_async(dispatch_get_main_queue(), ^{
[self handleCatchwithError:error];
});
}).finally(^{
dispatch_async(dispatch_get_main_queue(), ^{
DDLogInfo(#".....finally");
});
});
}
The concept you're looking for is thenable chaining. You want to chain multiple promises in a for loop.
My Objective-C is really rusty - but it should look something like:
// create an array for the results
__block NSMutableArray *results = [NSMutableArray arrayWithCapacity:[urls count]];
// create an initial promise
PMKPromise *p = [PMKPromise promiseWithValue: nil]; // create empty promise
for (id url in urls) {
// chain
p = p.then(^{
// chain the request and storate
return [self.operationManager GET:url
parameters:nil].then(^(id responseObject, AFHTTPRequestOperation *operation) {
[results addObject:responseObject]; // reference to result
return nil;
});
});
}
p.then(^{
// all results available here
});
For those of us looking for a Swift 2.3 solution:
import PromiseKit
extension Promise {
static func resolveSequentially(promiseFns: [()->Promise<T>]) -> Promise<T>? {
return promiseFns.reduce(nil) { (fn1: Promise<T>?, fn2: (()->Promise<T>)?) -> Promise<T>? in
return fn1?.then({ (_) -> Promise<T> in
return fn2!()
}) ?? fn2!()
}
}
}
Note that this function returns nil if the promises array is empty.
Example of use
Below is an example of how to upload an array of attachments in sequence:
func uploadAttachments(attachments: [Attachment]) -> Promise<Void> {
let promiseFns = attachments.map({ (attachment: Attachment) -> (()->Promise<Void>) in
return {
return self.uploadAttachment(attachment)
}
})
return Promise.resolveSequentially(promiseFns)?.then({}) ?? Promise()
}
func uploadAttachment(attachment: Attachment) -> Promise<Void> {
// Do the actual uploading
return Promise()
}
Thanks for Vegard's answer and I rewrite for Swift 3:
extension Promise {
static func resolveSequentially(promiseFns: [()->Promise<T>]) -> Promise<T>? {
return promiseFns.reduce(nil) { (fn1: Promise<T>?, fn2: (()->Promise<T>)?) -> Promise<T>? in
return fn1?.then{ (_) -> Promise<T> in
return fn2!()
} ?? fn2!()
}
}
}
/* Example */
func uploadAttachments(_ attachments: [Attachment]) -> Promise<Void> {
let promiseFns = attachments.map({ (attachment: Attachment) -> (()->Promise<Void>) in
return {
return self. uploadAttachment(attachment)
}
})
return Promise.resolveSequentially(promiseFns: promiseFns)?.then{Void -> Void in} ?? Promise { Void -> Void in }
}
Here is code for two closures in two different IBAction button presses. The desired outcome is for the button press to turn on/off an LED, then to access a light sensor and read the light value after the change in LED status.
What happens is a race condition where the function getVariable runs and returns before the callFunction has implemented the change. The result is that the value displayed in getLightLabel.text is that of the prior condition, not the current condition.
My question is how to rewrite the code below so that myPhoton!.getVariable does not execute until after the myPhoton!.callFunction has returned (completed its task).
I have tried placing getVariable inside callFunction, both before and after the } closing if (error == nil), but the result was identical to the code shown here.
#IBAction func lightOn(sender: AnyObject) {
let funcArgs = [1]
myPhoton!.callFunction("lightLed0", withArguments: funcArgs) { (resultCode : NSNumber!, error : NSError!) -> Void in
if (error == nil) {
self.lightStateLabel.text = "LED is on"
}
}
myPhoton!.getVariable("Light", completion: { (result:AnyObject!, error:NSError!) -> Void in
if let e = error {
self.getLightLabel.text = "Failed reading light"
}
else {
if let res = result as? Float {
self.getLightLabel.text = "Light level is \(res) lumens"
}
}
})
}
#IBAction func lightOff(sender: AnyObject) {
let funcArgs = [0]
myPhoton!.callFunction("lightLed0", withArguments: funcArgs) { (resultCode : NSNumber!, error : NSError!) -> Void in
if (error == nil) {
self.lightStateLabel.text = "LED is off"
}
}
myPhoton!.getVariable("Light", completion: { (result:AnyObject!, error:NSError!) -> Void in
if let e = error {
self.getLightLabel.text = "Failed reading light"
}
else {
if let res = result as? Float {
self.getLightLabel.text = "Light level is \(res) lumens"
}
}
})
}
Here is the callFunction comments and code from the .h file. This SDK is written in Objective C. I am using it in Swift with a bridging header file.
/**
* Call a function on the device
*
* #param functionName Function name
* #param args Array of arguments to pass to the function on the device. Arguments will be converted to string maximum length 63 chars.
* #param completion Completion block will be called when function was invoked on device. First argument of block is the integer return value of the function, second is NSError object in case of an error invoking the function
*/
-(void)callFunction:(NSString *)functionName withArguments:(NSArray *)args completion:(void (^)(NSNumber *, NSError *))completion;
/*
-(void)addEventHandler:(NSString *)eventName handler:(void(^)(void))handler;
-(void)removeEventHandler:(NSString *)eventName;
*/
Here is the .m file code
-(void)callFunction:(NSString *)functionName withArguments:(NSArray *)args completion:(void (^)(NSNumber *, NSError *))completion
{
// TODO: check function name exists in list
NSURL *url = [self.baseURL URLByAppendingPathComponent:[NSString stringWithFormat:#"v1/devices/%#/%#", self.id, functionName]];
NSMutableDictionary *params = [NSMutableDictionary new]; //[self defaultParams];
// TODO: check response of calling a non existant function
if (args) {
NSMutableArray *argsStr = [[NSMutableArray alloc] initWithCapacity:args.count];
for (id arg in args)
{
[argsStr addObject:[arg description]];
}
NSString *argsValue = [argsStr componentsJoinedByString:#","];
if (argsValue.length > MAX_SPARK_FUNCTION_ARG_LENGTH)
{
// TODO: arrange user error/codes in a list
NSError *err = [self makeErrorWithDescription:[NSString stringWithFormat:#"Maximum argument length cannot exceed %d",MAX_SPARK_FUNCTION_ARG_LENGTH] code:1000];
if (completion)
completion(nil,err);
return;
}
params[#"args"] = argsValue;
}
[self setAuthHeaderWithAccessToken];
[self.manager POST:[url description] parameters:params success:^(AFHTTPRequestOperation *operation, id responseObject) {
if (completion)
{
NSDictionary *responseDict = responseObject;
if ([responseDict[#"connected"] boolValue]==NO)
{
NSError *err = [self makeErrorWithDescription:#"Device is not connected" code:1001];
completion(nil,err);
}
else
{
// check
NSNumber *result = responseDict[#"return_value"];
completion(result,nil);
}
}
} failure:^(AFHTTPRequestOperation *operation, NSError *error)
{
if (completion)
completion(nil,error);
}];
}
One solution is to put the second closure inside the first, where the first returns and provides and Error value. If no error,then execuet the second closure. That is one way to tightly couple the two closures without resorting to semaphores or other messaging schemes.
In this application, the problem I was encountering cannot be solved on the IOS/Swift side of the stack. The cloud API and embedded uP are not tightly coupled, so the cloud returns to the IOS with a completion before the full function code has run on the Particle uP.
The solution to this overall problem actually lies in either modifying the cloud API or adding some additional code to the uP firmware to tightly couple the process to the IOS app with additional communication.
I'm trying to implement the example LoopBack iOS app in Swift
Create a LoopBack iOS app: part one
and I'm having some trouble translating from the ObjectiveC
- (void) getBooks
{
//Error Block
void (^loadErrorBlock)(NSError *) = ^(NSError *error){
NSLog(#"Error on load %#", error.description);
};
void (^loadSuccessBlock)(NSArray *) = ^(NSArray *models){
NSLog(#"Success count %d", models.count);
self.tableData = models;
[self.myTable reloadData];
};
//This line gets the Loopback model "book" through the adapter defined in AppDelegate
LBModelRepository *allbooks = [[booksAppDelegate adapter] repositoryWithModelName:prototypeName];
//Logic - Get all books. If connection fails, load the error block, if it passes, call the success block and pass allbooks to it.
[allbooks allWithSuccess:loadSuccessBlock failure:loadErrorBlock];
};
Here's my version
func getBooks() {
var errorBlock = {
(error: NSError!) -> Void in
NSLog("Error on load %#", error.description)
}
var successBlock = {
(models: NSArray!) -> Void in
NSLog("Success count %d", models.count)
self.tableData = models
self.booksTable.reloadData()
}
// get the "book" model
var allBooks: LBModelRepository = adapter.repositoryWithModelName(prototypeName)
// get all books
allBooks.allWithSuccess(successBlock, errorBlock)
}
but I get a compiler error on the call to allWithSuccess:
Cannot convert the expressions type 'Void' to type 'LBModelAllSuccessBlock!'
What am I missing?
UPDATE:
If I declare the success block as follows, it works:
var successBlock = {
(models: AnyObject[]!) -> () in
self.tableData = models
self.booksTable.reloadData()
}
Thanks for the answer!!!!
If anyone is looking for the last version of Swift and LoopBack iOS SDK, it worked for me like this:
func getBooks() {
// Error Block
let errorBlock = {
(error: NSError!) -> Void in
NSLog("Error on load %#", error.description)
}
// Success Block
let successBlock = {
(models: [AnyObject]!) -> () in
self.tableData = models
self.myTable.reloadData()
}
// This line gets the Loopback model "book" through the adapter defined in AppDelegate
let allBooks:LBPersistedModelRepository = AppDelegate.adapter.repositoryWithModelName(prototypeName, persisted: true) as! LBPersistedModelRepository
// Logic - Get all books. If connection fails, load the error block, if it passes, call the success block and pass allbooks to it.
allBooks.allWithSuccess(successBlock, failure: errorBlock)
}