hsavit1

- (void)shiftKeyboardIfNecessary {
    CGRect viewFrame = self.view.frame;
    CGRect activeTextFieldFrame = self.activeTextField.frame;
    CGFloat bottomPadding = 4;
    
    // The lowest point visible on the screen is the height of the screen minus the height of the keyboard, then adjusted by the current position
    // of the view. So, if the view has already been shifted upwards (negative origin), then more of the lower part of the screen is visible.
    CGFloat lowestPointCoveredByKeyboard = -viewFrame.origin.y + viewFrame.size.height - self.keyboardFrame.size.height;
    
    // The active text field's lowest point is its origin.y + its height (so, if it was at y=200, and is 21px tall, then the lowest point is 221.

hsavit1

- (RACSignal *)fetchJSONFromURL:(NSURL *)url {
    
    NSParameterAssert(url);
    
    return [[RACSignal createSignal:^RACDisposable *(id<RACSubscriber> subscriber) {
        
        NSURLSession * session = [NSURLSession sharedSession];
        NSURLSessionDataTask * dataTask = [session dataTaskWithURL:url completionHandler:^(NSData * data, NSURLResponse * response, NSError * error) {
            
            if (data) {

hsavit1

#import "NSManagedObject+MVVM.h"
#import <RBCoreDataStack/NSManagedObject+RBCoreDataStack.h>

@implementation NSManagedObject (MVVM)

+ (RACSignal *)fetchAllSignalInContext:(NSManagedObjectContext *)context {
    return [self fetchAllSignalWithPredicate:nil inContext:context];
}

+ (RACSignal *)fetchAllSignalWithPredicate:(NSPredicate *)predicate inContext:(NSManagedObjectContext *)context {

hsavit1

@import Foundation;
@import UIKit;


typedef UITableViewCell *(^MVVMCellCreatorBlock)(UITableView * tableView, NSIndexPath * indexPath, id object);


@interface MVVMTableViewListDataSource : NSObject <UITableViewDataSource>

- (id)initWithObjects:(NSArray *)objects cellCreator:(MVVMCellCreatorBlock)block;

hsavit1

// show a network activity indicator when the search is being executed
RAC([UIApplication sharedApplication], networkActivityIndicatorVisible) =
  self.viewModel.searchCommand.executing;

hsavit1

///////
//signal
///////

//conventional
- (BOOL)isFormValid {
    return [self.usernameField.text length] > 0 &&
            [self.emailField.text length] > 0 &&
            [self.passwordField.text length] > 0 &&
            [self.passwordField.text isEqual:self.passwordVerificationField.text];

hsavit1

// creates a signal that fetches an image in the background, delivering
// it on the UI thread. This signal 'cancels' itself if the cell is re-used before the
// image is downloaded.
-(RACSignal *)signalForImage:(NSURL *)imageUrl {
  
  RACScheduler *scheduler = [RACScheduler schedulerWithPriority:RACSchedulerPriorityBackground];
  
  RACSignal *imageDownloadSignal = [[RACSignal createSignal:^RACDisposable *(id<RACSubscriber> subscriber) {
      NSData *data = [NSData dataWithContentsOfURL:imageUrl];
      UIImage *image = [UIImage imageWithData:data];

hsavit1

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

- (void) initialize {
  
  // set up access to twitter

hsavit1

RAC(self, timestamp) = [[RACObserve(self, model.timestamp) map:^id(NSDate *value) {
            return [[RACSignal createSignal:^RACDisposable *(id<RACSubscriber> subscriber) {
                NSUInteger days, hours, minutes, seconds;
                absoluteTimeUnitsSinceDate(value, &days, &hours, &minutes, &seconds);
                NSUInteger updateAfter = NSNotFound;
                NSString *currentValue = nil;
                if (days) {
                    currentValue = [NSString stringWithFormat:@"%ud", (unsigned int)days];
                }
                else if (hours) {

hsavit1

//the trick is to use replayLast or replayLazily signal operation, which basically creates buffer and hold in it cached value! 

- (void)getData:(id)inputParam forKey:(NSString *)key withCompletionBlock:(void (^)(id data, NSError *error)) {
    if (!_cache[key]) {
        RACSignal *dataSignal = [RACSignal createSignal:^RACDisposable *(id<RACSubscriber> subscriber) {
            id operation = _actualGetDataRequest(inputParam, ^(id data, NSError *error) {
                if (error) {
                    [subscriber sendError:error];
                }