如何根据随机NSString将图像加载到UIImageView？

Question

I read a book on Objective-C and made ​​a couple of simple applications, but still can't figure out how to do some easy things. For example, there are ten names of books and ten covers to them.I want make appear one random book name on the screen with it's cover. I can write something like this:

NSArray* bookNames = @[@"Harry Potter", @"Atlas Shrugged", @"The Financier"];
NSString* book= bookNames[arc4random()%bookNames.count];

Is it right? How can I load an image of cover to UIImageView depending on book name?

Answer 1

You need another NSArray where you have to store names of your images, on the same index as your bookNames. For example:

//Your Arrays bookNames for names and bookImages for name of your images
NSArray* bookNames = @[@"Harry Potter", @"Atlas Shrugged", @"The Financier"];
NSArray* bookImages = @[@"Harry-Potter.jpg", @"Atlas-Shrugged.jpg", @"The-Financier.jpg"];

//Setting a randomindex for your book
NSInteger yourRandomIndex = arc4random_uniform(bookNames.count);

//Getting your imageName and your bookName for your book at randomIndex
NSString* bookName= bookNames[yourRandomIndex];
NSString* bookImage= bookImages[yourRandomIndex];

//Setting your ImageView image and your bookName in a label from your strings
[imageView setImage:[UIImage imageNamed:bookImage]];
bookName.text = bookName;

Answer 2

In cases like these, I usually create a (small) class, let's call it Books, with two properties:

@property (nonatomic, strong) NSString *bookTitle;
@property (nonatomic, strong) NSString *bookImage;

Create a static method that returns a new book object:

+ (Books *)createBookWithTitle:(NSString *)title andImage:(NSString *)image
{
    Books *book = [[Books alloc]init];

    book.bookTitle = title;
    book.bookImage = image;

    return book;
}

Then, you create an array, and add Books objects to it:

NSArray *books = @[[Books createBookWithTitle:@"Harry Potter" andImage:@"HarryPotter.png"],
                   [Books createBookWithTitle:@"Atlas Shrugged" andImage:@"Atlas Shrugged.png"],
                       ];

Then, you can just use:

Books *selectedBook = books[randomNumber];

NSString *title = selectedBook.bookTitle;
UIImage *image = selectedBook.bookImage;

It looks like overkill, but it clean and easy to work with. They pair very nicely that way.

Answer 3

UIImageView *yourImageView = ...
    NSArray* bookNames = @[@"Harry Potter", @"Atlas Shrugged", @"The Financier"];
NSString* book= bookNames[arc4random()%bookNames.count];
[yourImageView setImage:[UIImage imageNamed:book]];

Hope this helps