WFGoogleTranslateSessionManager

WFGoogleTranslateSessionManager.h

//
//  WFGoogleTranslateSessionManager.h
//
//  Created by Conrad Kramer on 2/9/15.
//  Copyright (c) 2015 DeskConnect. All rights reserved.
//

#import <Foundation/Foundation.h>

NS_ASSUME_NONNULL_BEGIN

@interface WFGoogleTranslateSessionManager : NSObject

@property (nonatomic, readonly, strong) NSURLSession *session;
@property (nonatomic, copy, nullable) NSString *apiKey;
@property (nonatomic, copy, nullable) NSString *referer;

- (instancetype)initWithSessionConfiguration:(nullable NSURLSessionConfiguration *)configuration NS_DESIGNATED_INITIALIZER;

- (void)getAvailableLanguages:(void (^)(NSArray * __nullable languages, NSError * __nullable error))completion;

- (void)translateStrings:(NSArray<NSString *> *)strings fromLanguage:(nullable NSString *)from intoLanguage:(NSString *)to completion:(void (^)(NSArray<NSString *> * __nullable strings, NSError * __nullable error))completion;
- (void)detectLanguagesOfStrings:(NSArray<NSString *> *)strings completion:(void (^)(NSArray<NSString *> * __nullable languages, NSError * __nullable error))completion;

@end

extern NSString * const WFGoogleTranslateErrorDomain;

NS_ASSUME_NONNULL_END

WFGoogleTranslateSessionManager.m

//
//  WFGoogleTranslateSessionManager.m
//
//  Created by Conrad Kramer on 2/9/15.
//  Copyright (c) 2015 DeskConnect. All rights reserved.
//

#import <UIKit/UIKit.h>

#import "WFGoogleTranslateSessionManager.h"

NS_ASSUME_NONNULL_BEGIN

@interface WFGoogleTranslateSessionManager ()

@property (nonatomic, readonly, copy) NSURL *baseURL;

@end

NSString * const WFGoogleTranslateErrorDomain = @"WFGoogleTranslateErrorDomain";

static NSString * const WFGoogleTranslateBaseURLString = @"https://www.googleapis.com/language/translate/v2";

@implementation WFGoogleTranslateSessionManager

- (instancetype)init {
    return [self initWithSessionConfiguration:nil];
}

- (instancetype)initWithSessionConfiguration:(nullable NSURLSessionConfiguration *)configuration {
    self = [super init];
    if (!self)
        return nil;
    
    _session = [NSURLSession sessionWithConfiguration:(configuration ?: [NSURLSessionConfiguration defaultSessionConfiguration])];
    _baseURL = [NSURL URLWithString:WFGoogleTranslateBaseURLString];
    
    return self;
}

- (void)getAvailableLanguages:(void (^)(NSArray * __nullable languages, NSError * __nullable error))completion {
    NSURL *url = [self.baseURL URLByAppendingPathComponent:@"languages"];
    [self sendRequestWithURL:url withParameters:nil completion:^(NSDictionary *response, NSError *error) {
        completion([response valueForKeyPath:@"data.languages.language"], error);
    }];
}

- (void)detectLanguagesOfStrings:(NSArray<NSString *> *)strings completion:(void (^)(NSArray<NSString *> * __nullable languages, NSError * __nullable error))completion {
    NSMutableArray<NSURLQueryItem *> *parameters = [NSMutableArray new];
    for (NSString *string in strings)
        [parameters addObject:[NSURLQueryItem queryItemWithName:@"q" value:string]];
    
    NSURL *url = [self.baseURL URLByAppendingPathComponent:@"detect"];
    [self sendRequestWithURL:url withParameters:parameters completion:^(NSDictionary *response, NSError *error) {
        NSMutableArray *languages = [NSMutableArray new];
        for (NSArray *possibilities in [response valueForKeyPath:@"data.detections.language"])
            [languages addObject:possibilities.firstObject];
        
        completion(languages, error);
    }];
}

- (void)translateStrings:(NSArray<NSString *> *)strings fromLanguage:(nullable NSString *)from intoLanguage:(NSString *)to completion:(void (^)(NSArray<NSString *> * __nullable strings, NSError * __nullable error))completion {
    if (!strings.count)
        return completion(@[], nil);
    
    NSMutableArray<NSURLQueryItem *> *parameters = [NSMutableArray new];
    if (from)
        [parameters addObject:[NSURLQueryItem queryItemWithName:@"source" value:from]];
    
    [parameters addObject:[NSURLQueryItem queryItemWithName:@"target" value:to]];
    
    for (NSString *string in strings)
        [parameters addObject:[NSURLQueryItem queryItemWithName:@"q" value:string]];

    [self sendRequestWithURL:self.baseURL withParameters:parameters completion:^(NSDictionary *response, NSError *error) {
        NSArray<NSString *> *responseStrings = [response valueForKeyPath:@"data.translations.translatedText"];
        if (!responseStrings.count)
            return completion(nil, error);
        
        // Decode HTML entities
        dispatch_async(dispatch_get_main_queue(), ^{
            NSError *innerError = error;
            NSDictionary *options = @{NSDocumentTypeDocumentAttribute: NSHTMLTextDocumentType, NSCharacterEncodingDocumentAttribute: @(NSUTF8StringEncoding)};
            NSMutableArray *cleanedStrings = [NSMutableArray new];
            
            for (NSString *string in responseStrings) {
                NSAttributedString *attributedString = [[NSAttributedString alloc] initWithData:[string dataUsingEncoding:NSUTF8StringEncoding] options:options documentAttributes:nil error:&innerError];
                [cleanedStrings addObject:(attributedString.string ?: string)];
            }
            
            completion([cleanedStrings copy], innerError);
        });
    }];
}

- (void)sendRequestWithURL:(NSURL *)url withParameters:(nullable NSArray<NSURLQueryItem *> *)parameters completion:(void (^)(NSDictionary * __nullable response, NSError * __nullable error))completion {
    NSMutableArray *queryItems = [NSMutableArray arrayWithArray:parameters];
    if (self.apiKey)
        [queryItems insertObject:[NSURLQueryItem queryItemWithName:@"key" value:self.apiKey] atIndex:0];
    
    NSData *body = ({
        NSURLComponents *components = [NSURLComponents new];
        components.queryItems = queryItems;
        [components.percentEncodedQuery dataUsingEncoding:NSUTF8StringEncoding];
    });
    
    NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:url];
    [request setHTTPMethod:@"POST"];
    [request setValue:@"GET" forHTTPHeaderField:@"X-HTTP-Method-Override"];
    [request setValue:self.referer forHTTPHeaderField:@"Referer"];
    [request setHTTPBody:body];
    
    [[self.session dataTaskWithRequest:request completionHandler:^(NSData * __nullable data, NSURLResponse * __nullable response, NSError * __nullable error) {
        if (!data.length)
            return completion(nil, error);
        
        NSDictionary *responseObject = [NSJSONSerialization JSONObjectWithData:data options:0 error:&error];
        NSDictionary *errorObject = responseObject[@"error"];
        if (errorObject) {
            NSMutableDictionary *userInfo = [NSMutableDictionary new];
            [userInfo setValue:errorObject[@"message"] forKey:NSLocalizedDescriptionKey];
            NSInteger code = [errorObject[@"code"] integerValue];
            error = [NSError errorWithDomain:WFGoogleTranslateErrorDomain code:code userInfo:userInfo];
        }
        
        completion(responseObject, error);
    }] resume];
}

@end

NS_ASSUME_NONNULL_END