Download Image and UIButton BG image - iphone

Question

I am trying to do download some images from server then , set these images as background image for some UIButtons .
so first downloading images :
NSString *urlMag1 = [NSString stringWithFormat:#"http://myweb.com/i224_mag1.png"];
NSString *urlMag2 = [NSString stringWithFormat:#"http://myweb.com/i224_mag2.png"];
NSString *str = [NSString stringWithFormat:urlMag1,urlMag2,nil];
NSData *data = [NSData dataWithContentsOfFile:str];
NSString *path = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) objectAtIndex:0];
[data writeToFile:path atomically:YES];
UIImage *imgMag1 = [UIImage imageNamed:#"i224_mag2.png"];
[mag2 setBackgroundImage:imgMag1 forState:UIControlStateNormal];
but nothing happens !!,and how can I check to if these images are in directory to avoid more downloading
I would be grateful if you help me to solve this
thanks !
EDITED
#Fernando Cervantes
I created a method to set buttons BG images something like this , but I don't know why does not work !
- (UIImage *)loadImages :(NSString *)fileNames ofType:(NSString *)extension inDirectory:(NSString *)directoryPath {
[[NSFileManager defaultManager] fileExistsAtPath:[directoryPath stringByAppendingPathComponent:[NSString stringWithFormat:#"%#.%#", fileNames, extension]]];
return 0;
}
and set BG images :
- (void)buttonsBGImage {
UIImage * bgMag2 = [self loadImages:#"i224_mag2" ofType:#"png" inDirectory:[NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) objectAtIndex:0]];
[mag2 setBackgroundImage:bgMag2 forState:UIControlStateNormal];
}
but actually nothing happens ! even I check the file and it's in app directory

Answer 1

The following approach might help you out a bit.
Save
-(void) saveFile:(NSString *)fileName ofType:(NSString *)extension fromURL:(NSString *)fileIndexPath inDirectory:(NSString *)directoryPath {
NSData * data = [NSData dataWithContentsOfURL:[NSURL URLWithString:fileIndexPath]];
[data writeToFile:[NSString stringWithFormat:#"%#/%#.%#", directoryPath, fileName, extension] atomically:YES];
}
Check
-(BOOL) checkIfFileExists:(NSString *)fileName ofType:(NSString *)extension inDirectoryPath:(NSString *)directoryPath {
bool result;
if ([[NSFileManager defaultManager] fileExistsAtPath:[directoryPath stringByAppendingPathComponent:[NSString stringWithFormat:#"%#.%#", fileName, extension]]]) {
result = TRUE;
} else {
result = FALSE;
}
return result;
}
Set
UIButton * button = [[UIButton alloc] init];
UIImage * backgroundImage = [self loadImage:#"YourImageName" ofType:#"png" inDirectory:[NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) objectAtIndex:0]];
[button setImage:backgroundImage forState:UIControlStateNormal];
-Edited-
I believe your problem is that you are returning 0 in your loadImages method. Instead of returning the image itself.
This is how I accomplished it:
Load
-(UIImage *) loadImage:(NSString *)fileName ofType:(NSString *)extension inDirectory:(NSString *)directoryPath {
UIImage * result = [UIImage imageWithContentsOfFile:[NSString stringWithFormat:#"%#/%#.%#", directoryPath, fileName, extension]];
return result;
}

Answer 2

[UIImage imageNamed:#"i224_mag2.png"]; // it is only for bundle. You should use
[UIImage imageWithContentsOfFile:path]
or
[UIImage imageWithData:data];
Update:
I use category for UIButton class.
- (void)loadImage:(NSString *)URL withActivityIndicator:(BOOL)hasActivity refreshObject:(UIView *)refresh{
// load image from cache cutted
dispatch_queue_t concurrentQueue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);
//this will start the image loading in bg
dispatch_async(concurrentQueue, ^{
NSData *image = [[NSData alloc] initWithContentsOfURL:[NSURL URLWithString:URL]];
//this will set the image when loading is finished
dispatch_async(dispatch_get_main_queue(), ^{
UIImage *loadedImage = [UIImage imageWithData:image];
// add image to cache cutted
[self setImage:loadedImage forState:UIControlStateNormal];
});
});
}

Answer 3

You are making NSData using dataWithContentsOfFile: API. you should use dataWithContentsOfURL instead.
NSString *urlMag1 = [NSString stringWithFormat:#"http://myweb.com/i224_mag1.png"];
NSString *urlMag2 = [NSString stringWithFormat:#"http://myweb.com/i224_mag2.png"];
NSData *image1 = [NSdata contentsOfURL:[NSURL URLWithString:urlMag1]];
NSData *image2 = [NSdata contentsOfURL:[NSURL URLWithString:urlMag2]];
[mag2 setBackgroundImage:imgMag1 forState:UIControlStateNormal];
Usually [NSdata contentsOfURL:[NSURL URLWithString:urlMag1]]; will freeze UI until image downloading complete.