FullScreen Image in UICollectionView on cell tap - ios

Question

I am using SDWebImage to show image in UICollectionView. I am getting productImageUrl and productId as server response. Able to show the image in Custom-cell, now what I want is:
1) Display the image in large view with a UIButton(buyButton) on another UIViewController named ProductDetailViewController.(Image is showing on the ProductDetailViewController but the way i am passing image url from ProductCollectionViewController is not right I think, please review the code and suggest me some better way to do it )
2) On button click a call will be made to the server with the productId which I got earlier as Server Response.(How would I pass the dictId to ProductDetailViewController so that I can make a call to the server).
3) Getting only two key-value of an Object as response, so its ok to parse it in multiple dictionary for multiple value. But If the response contain multiple value, what will be the optimized way to parse the response.
Here is the code which i have tried.
(Sorry for long unoptimized code, still in learning phase)
ProductCollectionViewController.m
#import "ProductCollectionViewController.h"
#import "ProductCell.h"
#import "UIImageView+WebCache.h"
#import "ProductDetailViewController.h"
#interface ProductCollectionViewController ()
#property(strong, nonatomic) NSMutableArray *productList;
#end
#implementation ProductCollectionViewController
-(id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
if (self) {
}
return self;
}
static NSString * const reuseIdentifier = #"Cell";
-(void)viewDidLoad
{
[super viewDidLoad];
[self getProductList];
}
-(void)didReceiveMemoryWarning {
[super didReceiveMemoryWarning];
}
-(void)getProductList
{
NSURL * url = [NSURL URLWithString:#"xxxx.yyyy.zzzz"];
NSMutableURLRequest * urlRequest = [NSMutableURLRequest requestWithURL:url];
NSURLSessionConfiguration *defaultConfigObject = [NSURLSessionConfiguration defaultSessionConfiguration];
NSURLSession *defaultSession = [NSURLSession sessionWithConfiguration: defaultConfigObject];
NSURLSessionDataTask * dataTask = [defaultSession dataTaskWithRequest:urlRequest completionHandler:^(NSData *data, NSURLResponse *response, NSError *error){
if (!error)
{
NSDictionary *responseJson = [NSJSONSerialization JSONObjectWithData:data options:kNilOptions error:nil];
NSArray *rsBody = responseJson[#"rsBody"];
_productList = [NSMutableArray new];
for(NSDictionary *dict in rsBody)
{
NSMutableDictionary *dictUrl=[[NSMutableDictionary alloc]init];
NSMutableDictionary *dictProductId =[[NSMutableDictionary alloc]init];
[dictUrl setValue:[dict valueForKey:#"productImageUrl"] forKey:#"url"];
[dictId setValue:[dict valueForKey:#"productId"] forKey:#"id"];
[_productList addObject:dictUrl];
[_productList addObject:dictId];
}
NSLog(#"urls for image: %#",_productList );
[self.collectionView reloadData];
}}];
[dataTask resume];
}
#pragma mark <UICollectionViewDataSource>
-(NSInteger)numberOfSectionsInCollectionView:(UICollectionView *)collectionView {
return 1;
}
-(NSInteger)collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section
{
return _productList.count;
}
- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath {
ProductCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:#"Cell" forIndexPath:indexPath];
NSURL *imageUrl = [[_productList objectAtIndex:indexPath.row]valueForKey:#"url"];
[cell.productImageView sd_setImageWithURL:imageUrl placeholderImage:[UIImage imageNamed:#"placeholder.jpg"]];
NSString *id =[[_productList objectAtIndex:indexPath.row] valueForKey:#"id"];
cell.productPrice.text= id;
return cell;
}
- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender {
if ([segue.identifier isEqualToString:#"showProduct"]) {
NSArray *indexPaths = [self.collectionView indexPathsForSelectedItems];
ProductDetailViewController *destViewController = segue.destinationViewController;
NSIndexPath *indexPath = [indexPaths objectAtIndex:0]
destViewController.productName =[[_productList objectAtIndex:indexPath.row]valueForKey:#"url"];
[self.collectionView deselectItemAtIndexPath:indexPath animated:NO];
}
}
#end
ProductDetailViewController.h
`#import <UIKit/UIKit.h>
#interface ProductDetailViewController : UIViewController
- (IBAction)buyButton:(id)sender;
- (IBAction)closeButton:(id)sender;
#property (weak, nonatomic) IBOutlet UIImageView *productImage;
#property (weak, nonatomic) NSString *productName;
#end`
ProductDetailViewController.m
- (void)viewDidLoad {
[super viewDidLoad];
self.productImage.image = [UIImage imageWithData:[NSData dataWithContentsOfURL:[NSURL URLWithString:self.productName]]];
//code to get productId
}
- (IBAction)buyButton:(id)sender {
//code to make server call with productId.
}
Server Response Format in JSON
{"rsBody":
[{"productId":11,
"productImageUrl":"http:xxxx"},
{"productId":9,
"productImageUrl":"http:"xxxx"}]}

Answer 1

For your first question, this line
self.productImage.image = [UIImage imageWithData:[NSData dataWithContentsOfURL:[NSURL URLWithString:self.productName]]];
is blocking the main thread. Meaning the app will go to the server download the entire image before updating the screen or allowing interactions, which is bad.
NSURL *url = [[NSURL alloc]initWithString:self.productName];
dispatch_queue_t imageFetchQ = dispatch_queue_create("image fetcher", NULL);
dispatch_async(imageFetchQ, ^{
NSData *imageData = [[NSData alloc] initWithContentsOfURL:url];
UIImage *image = [[UIImage alloc]initWithData:imageData];
dispatch_async(dispatch_get_main_queue(), ^{
self.productImage.image=image;
}
});
});
Try the block above instead. It will fetch the product image on a different thread.
Question two: Two transfer data between view controllers do what you're doing in prepareForSegue setup the public properties of the destination view controller.
Question three: Optimum way is to create an NSObject class that you read the data from the dictionary into properties on that class through some method called like setupFromDictionary.
Here you would have an Object called product with a productID property and productImageURL property. That way you're not constantly calling valueForKey or objectForKey on some dictionary.