A network layer using ReactiveCocoa

PASDataSource.h

#import <Foundation/Foundation.h>
#import <ReactiveCocoa/ReactiveCocoa.h>

@interface PASDataSource : NSObject

@property (nonatomic, strong, readonly) NSArray *passes;

+ (PASDataSource *)sharedInstance;
- (RACSignal *)refreshPassInfoSignal;

@end

PASDataSource.m

#import "PASDataSource.h"
#import "PASConstants.h"

#import "PASPassDetailCell.h"
#import "PASPass.h"

#import "PASSignaller.h"

#import <EXTScope.h>
#import <HexColor.h>

@interface PASDataSource ()

@property (nonatomic, strong, readwrite) NSArray *passes;
@property (nonatomic, strong, readwrite) PASSignaller *dataRetriever;

@property (nonatomic, strong, readwrite) NSMutableArray *tempPasses;
@property (nonatomic, strong) NSDateFormatter *dateFormatter;

@end

@implementation PASDataSource

- (NSDateFormatter *)dateFormatter {
    if (!_dateFormatter) {
        _dateFormatter = [[NSDateFormatter alloc] init];
        [_dateFormatter setDateStyle:NSDateFormatterMediumStyle];
        [_dateFormatter setTimeStyle:NSDateFormatterShortStyle];
    }
    
    return _dateFormatter;
}

+ (PASDataSource *)sharedInstance {
    static PASDataSource *_sharedInstance = nil;
    static dispatch_once_t onceToken;
    dispatch_once(&onceToken, ^{
        _sharedInstance = [[PASDataSource alloc] init];
    });
    
    return _sharedInstance;
}

- (id)init {
    if ((self = [super init])) {
        self.passes = [self initialModel];
        self.dataRetriever = [[PASSignaller alloc] init];
        
        [[self refreshPassInfoSignal] subscribeCompleted:^{
            [[NSNotificationCenter defaultCenter] postNotificationName:PASPassesDidUpdateNotification object:nil];
        }];
    }
    
    return self;
}

- (NSDictionary *)seedDictionary {
    NSDictionary *dictionary = @{@"Snoqualmie": @"http://www.wsdot.com/traffic/passes/snoqualmie/",
                                 @"Stevens": @"http://www.wsdot.com/traffic/passes/stevens/",
                                 @"White": @"http://www.wsdot.com/traffic/passes/white/",
                                 @"Status": @"http://www.wsdot.com/traffic/passes/satus/default.aspx",
                                 @"Manastash Ridge": @"http://www.wsdot.com/traffic/passes/manastash/default.aspx",
                                 @"Blewett": @"http://www.wsdot.com/traffic/passes/blewett/default.aspx"};
    return dictionary;
}

- (NSArray *)initialModel {
    NSMutableArray *array = [NSMutableArray array];
    [[self seedDictionary] enumerateKeysAndObjectsUsingBlock:^(id key, id obj, BOOL *stop) {
        PASPass *pass = [[PASPass alloc] init];
        [pass setTitle:key];
        [pass setReferenceURL:[NSURL URLWithString:obj]];
        [pass setUniqueId:[pass.referenceURL hash]];
        [array addObject:pass];
    }];
    
    return [NSArray arrayWithArray:array];
}

- (RACSignal *)refreshPassInfoSignal {
    NSMutableArray *signals = [NSMutableArray array];
    [self.passes enumerateObjectsUsingBlock:^(PASPass *pass, NSUInteger idx, BOOL *stop) {
        NSDictionary *info = @{@"referenceURL": pass.referenceURL, @"title": pass.title};
        RACSignal *signal = [self.dataRetriever passInfoForURL:pass.referenceURL info:info];
        [signals addObject:signal];
    }];
    
    RACReplaySubject *subject = [RACReplaySubject subject];
    
    @weakify(self);
    NSMutableArray *passes = [NSMutableArray array];
    [[RACSignal merge:signals] subscribeNext:^(PASPass *pass) {
        NSAssert([pass isKindOfClass:[PASPass class]], @"Wrong class type");
        [passes addObject:pass];
    } completed:^{
        @strongify(self);
        self.passes = [NSArray arrayWithArray:passes];
        [subject sendCompleted];
    }];
    
    return [subject deliverOn:[RACScheduler mainThreadScheduler]];
}

PASParser.h

#import <Foundation/Foundation.h>

@interface PASParser : NSObject

+ (PASParser *)parser;
- (NSDictionary *)parsePassFromResponse:(NSData *)response;

@end

PASParser.m

#import "PASParser.h"
#import <TFHpple.h>

@implementation PASParser

+ (PASParser *)parser {
    return [[self alloc] init];
}

- (id)init {
    if ((self = [super init])) {
        //
    }
    return self;
}

- (NSDictionary *)parsePassFromResponse:(NSData *)response {
    TFHpple *parser = [TFHpple hppleWithHTMLData:response];
    NSMutableDictionary *dictionary = [NSMutableDictionary dictionary];
    
    [[self queryDictionary] enumerateKeysAndObjectsUsingBlock:^(id key, id obj, BOOL *stop) {
        NSString *result = [self contentAtXPath:obj usingParser:parser];
        if (result) {
            [dictionary setObject:result forKey:key];
        } else {
            [dictionary setObject:[NSNull null] forKey:key];
        }
    }];
    
    return [NSDictionary dictionaryWithDictionary:dictionary];
}

- (NSString *)contentAtXPath:(NSString *)xpath usingParser:(TFHpple *)parser {
    NSString *content = nil;
    NSArray *results = [parser searchWithXPathQuery:xpath];
    
    if (results.count > 0) {
        content = [[[results firstObject] firstChild] content];
    }
    
    return content;
}

- (NSDictionary *)queryDictionary {
    NSDictionary *queryDictionary = @{@"conditions": @"//span[@id='PassInfoConditions']",
                                      @"eastbound": @"//span[@id='PassInfoRestrictionsOne']",
                                      @"westbound": @"//span[@id='PassInfoRestrictionsTwo']",
                                      @"last_updated": @"//span[@id='PassInfoLastUpdate']"};
    return queryDictionary;
}

@end

PASPass.h

#import <Foundation/Foundation.h>
#import <Mantle.h>

NS_ENUM(NSUInteger, PASPassStatusType) {
    PASPassStatusOpen = 1001,
    PASPassStatusRestricted,
    PASPassStatusClosed
};

@interface PASPass : MTLModel <MTLJSONSerializing>

@property (nonatomic, copy) NSString *title;
@property (nonatomic, copy) NSString *conditions;
@property (nonatomic, copy) NSString *eastbound;
@property (nonatomic, copy) NSString *westbound;

@property (nonatomic, copy) NSURL *referenceURL;
@property (nonatomic, copy) NSDate *lastUpdated;

@property (nonatomic) NSUInteger uniqueId;

- (BOOL)isOpen;
- (BOOL)isClosed;

@end

PASSignaller.h

#import <Foundation/Foundation.h>
#import <AFNetworking/AFNetworking.h>
#import <ReactiveCocoa/ReactiveCocoa.h>

@interface PASSignaller : NSObject

- (RACSignal *)passInfoForURL:(NSURL *)url info:(NSDictionary *)info;

@end

PASSignaller.m

#import "PASSignaller.h"
#import "PASParser.h"
#import "PASPass.h"

@interface PASSignaller ()

- (RACSignal *)signalForURLRequest:(NSURLRequest *)request;

@end

@implementation PASSignaller

- (instancetype)init {
    if ((self = [super init])) {
        //
    }
    
    return self;
}

- (RACSignal *)passInfoForURL:(NSURL *)url info:(NSDictionary *)info {
    NSURLRequest *request = [NSURLRequest requestWithURL:url];
    RACSignal *signal = [[self signalForURLRequest:request] map:^id(id responseObj) {
        PASParser *parser = [[PASParser alloc] init];
        NSDictionary *parsedResponse = [parser parsePassFromResponse:responseObj];
        
        NSMutableDictionary *passObj = [NSMutableDictionary dictionaryWithDictionary:parsedResponse];
        PASPass *pass = [MTLJSONAdapter modelOfClass:[PASPass class] fromJSONDictionary:passObj error:nil];
        [pass setUniqueId:[pass.referenceURL hash]];
        [pass setConditions:pass.conditions];
        [pass setTitle:pass.title];
        
        [info enumerateKeysAndObjectsUsingBlock:^(id key, id obj, BOOL *stop) {
            [pass setValue:obj forKey:key];
        }];
        
        return pass;
    }];
    
    return signal;
}

#pragma mark - Private
- (RACSignal *)signalForURLRequest:(NSURLRequest *)request {
    RACReplaySubject *subject = [RACReplaySubject subject];
    
    AFHTTPRequestOperation *operation = [[AFHTTPRequestOperation alloc] initWithRequest:request];
    [operation setResponseSerializer:[AFHTTPResponseSerializer serializer]];
    [operation setCompletionBlockWithSuccess:^(AFHTTPRequestOperation *operation, id responseObject) {
        [subject sendNext:responseObject];
        [subject sendCompleted];
    } failure:^(AFHTTPRequestOperation *operation, NSError *error) {
        [subject sendError:error];
        [subject sendCompleted];
    }];
    
    [[NSOperationQueue mainQueue] addOperation:operation];
    
    return [subject deliverOn:[RACScheduler scheduler]];
}

@end