How to access NSDictionary by key number?

Question

I'm a beginner in iPhone development and I need some help.

I created an NSDictionary to hold some quotes followed by keys (which is the person who quoted them).

Now, I'v created a method to pull a random quote, and to use this method 'arc4random_uniform' I need to use integer...and them I do 'return [self.insperationalQuotes objectForKey:"here i want a random number"];

Usually it probably would be easier to use an array but I want to use the key to attach it to a specific photo of the person who quoted it...or you still recommend to do it with array and say object at #1 will einstein for instance...

This is my code:

#import "NOQuotes.h"

@implementation NOQuotes


- (NSDictionary *) insparationalQuotes {

    if (_insparationalQuotes == nil) {


        _insparationalQuotes = [[NSDictionary alloc] initWithObjectsAndKeys:
                                @"Try not to become a man of success but a man of value.",
                                @"ALBERT EINSTEIN",
                                @"What lies behind us and what lies before us are tiny matters compared to what lies within us.",
                                @"HENRY STANLEY HASKINS",
                                @"It is never too late to be what you might have been.",
                                @"GEORGE ELIOT",
                                @"All our dreams can come true–if we have the courage to pursue them.",
                                @"WALT DISNEY",
                                @"The best way to predict the future is to invent it.",
                                @"ALAN KAY",
                                @"You miss 100% of the shots you don’t take.",
                                @"WAYNE GRETZKY",
                                @"If opportunity doesn’t knock, build a door.",
                                @"MILTON BERLE",
                                @"Failure is the condiment that gives success its flavor.",
                                @"TRUMAN CAPOTE", nil];

    }

    return _insparationalQuotes;
}



- (NSString *) getRandomQuote {



    int randomNum = arc4random_uniform(self.insparationalQuotes.count);

    return [self.insparationalQuotes objectForKey:randomNum]; //error

}

Thanks!

Answer 1

For what you're trying to do, I recommend creating a Quote class, which will store a quote, an "author", and the image associated with that person. I'd then fill an NSArray or NSMutableArray with instances of these Quote objects so you can randomly select an index.

@interface Quote : NSObject

@property NSString *quote;
@property NSString *author;
@property UIImage *picture;

+(instancetype)quoteWithQuote:(NSString*)quote 
                       author:(NSString*)author 
                      picture:(UIImage*)picture;

-(instancetype)initWithQuote:(NSString*)quote  
                      author:(NSString*)author 
                     picture:(UIImage*)picture;

@end

Then just fill in that class. Arguably, you may even want the @propertys to be readonly, making the Quote class immutable.

---

Alternatively, you can keep your NSDictionary as is, and pair it with an NSArray made up of all the author names (which you're using as keys). Then select a random index from the array of names, and use that name as the key into the dictionary for the quote. The problem here is it's a little redundant, and you can't have multiple quotes with the same author.

Answer 2

Use allValues to pull an array of values, and index into that array using a random number, like this:

- (NSString *) getRandomQuote {
    int randomNum = arc4random_uniform(self.insparationalQuotes.count);
    return [[self.insparationalQuotes allValues] objectAtIndex:randomNum];
}

Answer 3

I agree that what you really want is an array of custom objects, but I would like to point out that it is possible to select a random entry from an NSDictionary object:

- (id)randomObjectInDictionary:(NSDictionary *)dict {
    NSArray *keyArray =  [dict allKeys];
    int rand = arc4random_uniform([keyArray count]);
    return dict[keyArray[rand]];
}