UICollectionViewController的简单使用及一些注意点(json)

UICollectionViewController在使用之前必须要做的两件事:

一. 为UICollectionViewController指定布局方式

二. 为UICollectionViewController注册单元格

流式布局小例子:

#import "SZMProductCollectionViewController.h"
#import "SZMProductModel.h"
#import "SZMProductCell.h"
@interface SZMProductCollectionViewController ()

@property (nonatomic,strong)NSArray *products;

@end

@implementation SZMProductCollectionViewController

static NSString * const reuseIdentifier = @"Cell";

- (NSArray *)products{
    if (!_products) {
        //加载数据
        
        //获取json文件路径
        NSString *path = [[NSBundle mainBundle]pathForResource:@"more_project.json" ofType:nil];
        //把json文件加载到一个NSData对象中
        NSData *jsonData = [NSData dataWithContentsOfFile:path];
        //把NSData转换为一个字典数组
        NSArray *arrayDicts = [NSJSONSerialization JSONObjectWithData:jsonData options:NSJSONReadingMutableContainers error:nil];
        //把字典数组转换为一个模型数组
        NSMutableArray *modelArray = [NSMutableArray array];
        for (NSDictionary *dict in arrayDicts) {
            SZMProductModel *modle = [SZMProductModel productWithDict:dict];
            [modelArray addObject:modle];
        }
        _products = modelArray;
    }
    return _products;
}

- (instancetype)init{
    //创建一个流式布局对象
    UICollectionViewFlowLayout *layout = [[UICollectionViewFlowLayout alloc]init];
    //设置每个cell的大小
    layout.itemSize = CGSizeMake(80, 80);
    //设置每个cell间的最小水平间距
    layout.minimumInteritemSpacing = 0;
    //设置每个cell间的行间距
    layout.minimumLineSpacing = 5;
    //设置每一组距离四周的内边距
    layout.sectionInset = UIEdgeInsetsMake(5, 0, 0, 0);
    
    //返回
    return [super initWithCollectionViewLayout:layout];
    
}
- (void)viewDidLoad {
    [super viewDidLoad];
    //注册类:注册单元格:告诉系统(UICollectionView),当缓存池中没有现成的cell对象以后,要创建哪个类的对象作为cell来使用
    //[self.collectionView registerClass:[UICollectionViewCell class] forCellWithReuseIdentifier:reuseIdentifier];
    
    //注册xib
    UINib *nib = [UINib nibWithNibName:@"SZMProductCell" bundle:nil];
    [self.collectionView registerNib:nib forCellWithReuseIdentifier:reuseIdentifier];
    
    [self.collectionView setBackgroundColor:[UIColor colorWithPatternImage:[UIImage imageNamed:@"bg"]]];
    
}

- (void)collectionView:(UICollectionView *)collectionView didSelectItemAtIndexPath:(NSIndexPath *)indexPath{
    
    SZMProductModel *model = self.products[indexPath.row];
    NSLog(@"%@",model.title);
}

- (void)didReceiveMemoryWarning {
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}

#pragma mark <UICollectionViewDataSource>
//返回多少组
- (NSInteger)numberOfSectionsInCollectionView:(UICollectionView *)collectionView {

    return 1;
}

//每组返回多少格子
- (NSInteger)collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section {

    return self.products.count;
}
//每个格子返回什么内容
- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath {
    
    //1.获取数据
    SZMProductModel *model = self.products[indexPath.row];
    //2.创建cell
    SZMProductCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:reuseIdentifier forIndexPath:indexPath];
    //3.为cell设置数据
    cell.product = model;
    
    
    return cell;
}


@end