CollectionView-Simple
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DESCRIPTION:
Demonstrates how to use UICollectionView, a way to present ordered data to users in a grid-like fashion. With a collection view object, you are able to define the presentation and arrangement of embedded views. The collection view class works closely with an accompanying layout object to define the placement of individual data items. In this example UIKit provides a standard flow-based layout object that you can use to implement multi-column grids containing items of a standard size.
When you run the sample, tap each image to navigate to a detailed view of that image. The app also shows how to implement a custom cell and custom selection by subclassing UICollectionViewCell.
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BUILD REQUIREMENTS:
iOS SDK 6.0
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RUNTIME REQUIREMENTS:
iOS 6.0
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Copyright (C) 2012 Apple Inc. All rights reserved.
- Design
File structure
- Code
AppDelegate.h
#import <UIKit/UIKit.h>
@interface AppDelegate : UIResponder <UIApplicationDelegate>
@end
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AppDelegate.m
#import "AppDelegate.h"
@implementation AppDelegate
@synthesize window = _window;
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
// Override point for customization after application launch.
return YES;
}
- (void)applicationWillResignActive:(UIApplication *)application
{
// Sent when the application is about to move from active to inactive state. This can occur for certain types of temporary interruptions (such as an incoming phone call or SMS message) or when the user quits the application and it begins the transition to the background state.
// Use this method to pause ongoing tasks, disable timers, and throttle down OpenGL ES frame rates. Games should use this method to pause the game.
}
- (void)applicationDidEnterBackground:(UIApplication *)application
{
// Use this method to release shared resources, save user data, invalidate timers, and store enough application state information to restore your application to its current state in case it is terminated later.
// If your application supports background execution, this method is called instead of applicationWillTerminate: when the user quits.
}
- (void)applicationWillEnterForeground:(UIApplication *)application
{
// Called as part of the transition from the background to the inactive state; here you can undo many of the changes made on entering the background.
}
- (void)applicationDidBecomeActive:(UIApplication *)application
{
// Restart any tasks that were paused (or not yet started) while the application was inactive. If the application was previously in the background, optionally refresh the user interface.
}
- (void)applicationWillTerminate:(UIApplication *)application
{
// Called when the application is about to terminate. Save data if appropriate. See also applicationDidEnterBackground:.
}
@end
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ViewController.h
#import <UIKit/UIKit.h>
@interface ViewController : UICollectionViewController
@end
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ViewController.m
#import "ViewController.h"
#import "DetailViewController.h"
#import "Cell.h"
NSString *kDetailedViewControllerID = @"DetailView"; // view controller storyboard id
NSString *kCellID = @"cellID"; // UICollectionViewCell storyboard id
@implementation ViewController
- (NSInteger)collectionView:(UICollectionView *)view numberOfItemsInSection:(NSInteger)section;
{
return 32;
}
- (UICollectionViewCell *)collectionView:(UICollectionView *)cv cellForItemAtIndexPath:(NSIndexPath *)indexPath;
{
// we're going to use a custom UICollectionViewCell, which will hold an image and its label
//
Cell *cell = [cv dequeueReusableCellWithReuseIdentifier:kCellID forIndexPath:indexPath];
// make the cell's title the actual NSIndexPath value
cell.label.text = [NSString stringWithFormat:@"{%ld,%ld}", (long)indexPath.row, (long)indexPath.section];
// load the image for this cell
NSString *imageToLoad = [NSString stringWithFormat:@"%d.JPG", indexPath.row];
cell.image.image = [UIImage imageNamed:imageToLoad];
return cell;
}
// the user tapped a collection item, load and set the image on the detail view controller
//
- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender
{
if ([[segue identifier] isEqualToString:@"showDetail"])
{
NSIndexPath *selectedIndexPath = [[self.collectionView indexPathsForSelectedItems] objectAtIndex:0];
// load the image, to prevent it from being cached we use 'initWithContentsOfFile'
NSString *imageNameToLoad = [NSString stringWithFormat:@"%d_full", selectedIndexPath.row];
NSString *pathToImage = [[NSBundle mainBundle] pathForResource:imageNameToLoad ofType:@"JPG"];
UIImage *image = [[UIImage alloc] initWithContentsOfFile:pathToImage];
DetailViewController *detailViewController = [segue destinationViewController];
detailViewController.image = image;
}
}
@end
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DetailViewController.h
#import <UIKit/UIKit.h>
@interface DetailViewController : UIViewController
@property (nonatomic, strong) UIImage *image;
@end
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DetailViewController.m
#import "DetailViewController.h"
@interface DetailViewController ()
@property (nonatomic, weak) IBOutlet UIImageView *imageView;
@end
@implementation DetailViewController
- (void)viewWillAppear:(BOOL)animated
{
[super viewWillAppear:animated];
self.imageView.image = self.image;
}
@end
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Cell.h
#import <UIKit/UIKit.h>
@interface Cell : UICollectionViewCell
@property (strong, nonatomic) IBOutlet UIImageView *image;
@property (strong, nonatomic) IBOutlet UILabel *label;
@end
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Cell.m
#import "Cell.h"
#import "CustomCellBackground.h"
@implementation Cell
- (id)initWithCoder:(NSCoder *)aDecoder
{
self = [super initWithCoder:aDecoder];
if (self)
{
// change to our custom selected background view
CustomCellBackground *backgroundView = [[CustomCellBackground alloc] initWithFrame:CGRectZero];
self.selectedBackgroundView = backgroundView;
}
return self;
}
@end
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CustomCellBackground.h
#import <UIKit/UIKit.h>
@interface CustomCellBackground : UIView
@end
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CustomCellBackground.m
#import "CustomCellBackground.h"
@implementation CustomCellBackground
- (void)drawRect:(CGRect)rect
{
// draw a rounded rect bezier path filled with blue
CGContextRef aRef = UIGraphicsGetCurrentContext();
CGContextSaveGState(aRef);
UIBezierPath *bezierPath = [UIBezierPath bezierPathWithRoundedRect:rect cornerRadius:5.0f];
[bezierPath setLineWidth:5.0f];
[[UIColor blackColor] setStroke];
UIColor *fillColor = [UIColor colorWithRed:0.529 green:0.808 blue:0.922 alpha:1]; // color equivalent is #87ceeb
[fillColor setFill];
[bezierPath stroke];
[bezierPath fill];
CGContextRestoreGState(aRef);
}
@end
Copyright (C) 2012 Apple Inc. All Rights Reserved.
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