Select Random Picture Within Array

[Samalope]

Hello,
I am pretty new to programming on iphone and have gotten stuck with something. I am trying to select a random picture from my array. Also, I only know how to make my array show as an animation and i was wondering how to make it so it just shows the image in the image view instead of animating it. I plan on having 300-500 images total. Thanks for any help! My code is attached.

[smasher]

Originally Posted by Samalope

Hello,
I am pretty new to programming on iphone and have gotten stuck with something. I am trying to select a random picture from my array. Also, I only know how to make my array show as an animation and i was wondering how to make it so it just shows the image in the image view instead of animating it. I plan on having 300-500 images total. Thanks for any help! My code is attached.

I did not look at your code, but It sounds like you're using a UIImageView and setting the animationImages property. If you set myView.animationImages = nil then you can set myView.image = anImage. That will display the single image "anImage".

300 images is a lot, probably too many to load into memory at the same time. Instead, you should probably keep an NSArray of image *filenames* , and when you pick your random number, take that filename and load the image.

[Samalope]

Originally Posted by smasher

I did not look at your code, but It sounds like you're using a UIImageView and setting the animationImages property. If you set myView.animationImages = nil then you can set myView.image = anImage. That will display the single image "anImage".

300 images is a lot, probably too many to load into memory at the same time. Instead, you should probably keep an NSArray of image *filenames* , and when you pick your random number, take that filename and load the image.

could you give me an example of what an NSArray of image *filenames* would look like? And would I use the arc4random() function with that?


I really appreciate your help! Thank You!

[mr-sk]

Yes,

You can do something like:

NSInteger *picToSelect = arc4random() % PICTURE_COUNT;
return [pictureArray objectAtindex:picToSelect];

or:

NSString *imageName = [pictureArray objectAtIndex:[arc4random() % PICTURE_COUNT]];

Where PICTURE_COUNT is the total # of images you have, and pictureArray is an NSArray(or muteable, etc) that stores all the image names.

That's just off the top of my head, so could be incorrect, but should help.

- sk

[smasher]

Originally Posted by Samalope

could you give me an example of what an NSArray of image *filenames* would look like? And would I use the arc4random() function with that?

I really appreciate your help! Thank You!

Something like this -

//create an array of filenames
NSMutableArray *fileNames = [[NSMutableArray alloc ] initWithObjects: @"one", @"a", @"two", @"b", @"three", @"four", nil];

//pick one filename
int numFileNames = [fileNames count];
int chosen = arc4random() % numFileNames;
NSString *oneFilename = [fileNames objectAtIndex: chosen];

//load your image here

[Samalope]

Originally Posted by mr-sk

Yes,

You can do something like:

NSInteger *picToSelect = arc4random() % PICTURE_COUNT;
return [pictureArray objectAtindex:picToSelect];

or:

NSString *imageName = [pictureArray objectAtIndex:[arc4random() % PICTURE_COUNT]];

Where PICTURE_COUNT is the total # of images you have, and pictureArray is an NSArray(or muteable, etc) that stores all the image names.

That's just off the top of my head, so could be incorrect, but should help.

- sk

Ok but do i still need to make the array like this:

[NSArray arrayWithObjects:
[UIImage imageNamed: @"name1.png"],
[UIImage imageNamed: @"name2.png"],
[UIImage imageNamed: @"name3.png"],
[UIImage imageNamed: @"name4.png"],
[UIImage imageNamed: @"name5.png"],
[UIImage imageNamed: @"name6.png"],
[UIImage imageNamed: @"name7.png"],

[UIImage imageNamed: @"name8.png"], nil];



And do that all the way up to 300? or would it just pull that from my resources folder? Thanks

[mr-sk]

Hey, you could do like:

for (int c=0;c<300;c++)
{
    NSString *imageName = [NSString stringWithFormat:@"name%d.png", c];
    [UIImage imageNamed: imageName];
}

Something like that?

[Samalope]

Originally Posted by mr-sk

Hey, you could do like:

for (int c=0;c<300;c++)
{
    NSString *imageName = [NSString stringWithFormat:@"name%d.png", c];
    [UIImage imageNamed: imageName];
}

Something like that?

Hi Mr Sk, that seems to be what i want to do. It does not do anything when i run it, I get the error:

"Terminating due to uncaught exception"

Do I need anything before or after that chunk of code you gave me?

[mr-sk]

heh sorry - try this:

NSMutableArray *imageArray;
for (int c=0;c<300;c++)
{
    NSString *imageName = [NSString stringWithFormat:@"name%d.png", c];
    [imageArray addObject: imageName];
}

Something like that. It should add all the objects to "imageArray".
Set a break point and make sure its working.

[Samalope]

Originally Posted by mr-sk

heh sorry - try this:

NSMutableArray *imageArray;
for (int c=0;c<300;c++)
{
    NSString *imageName = [NSString stringWithFormat:@"name%d.png", c];
    [imageArray addObject: imageName];
}

Something like that. It should add all the objects to "imageArray".
Set a break point and make sure its working.

Hey thanks for the all the info you gave us, it helped a lot. we did it a little bit differently than how you said but the info you gave us contributed to our success. We have a new problem though: the loaded image loads to the top left of the screen. I have another post with the specific info so if you know anything that could be going wrong, please tell us. Thanks again! The link is:

http://www.iphonedevsdk.com/forum/ip...rong-spot.html

[mr-sk]

Coolio man - glad we could help.

I'll take a peak at your other thread.

[noobforlife]

I been trying to accomplish something along the same lines but I only have about 10 images. I also want to have a options menu where I can turn groups of images off. So if the flick the switch of mountians off then no mountains will be generated. Since I only have about 10 image should I go with some more like this:

NSString *imagePath = [NSString stringWithFormat:@"image%d.png", (arc4random() % 10) + 1];

instead of a array