從URL獲取圖像並將其顯示到圖像庫AlAsset

Question

我知道這個問題可能會被問很多次，但是我是一個初學者，所以溫柔一點是一個謙虛的要求。

我正在嘗試制作一個圖像庫，以顯示URL的所有圖像。

我已經使用了所有資產框架，並制作了一個簡單的圖庫，可以返回相機膠卷的圖像，我想擁有一些URL的圖像，因此請幫助我從url獲取圖像並將其顯示在Image Gallery中

這是視圖控制器頭文件

#import <UIKit/UIKit.h>
#import <AssetsLibrary/AssetsLibrary.h>

@interface ViewController : UIViewController <UICollectionViewDelegate,UICollectionViewDataSource>
@property (retain, nonatomic) IBOutlet UICollectionView *collectionView;
@property(nonatomic, strong) NSArray *assets;

這是我已在其中注冊一個.NIB文件以將Cell添加到我的CollectionView的實現文件

#import "ViewController.h"
#import <AssetsLibrary/AssetsLibrary.h>
#import "MyCell.h"
@interface ViewController ()

@end

@implementation ViewController

- (void)viewDidLoad
{
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.
    [self.collectionView registerNib:[UINib nibWithNibName:@"MyCell" bundle:nil] forCellWithReuseIdentifier:@"CELL"];





_assets = [@[] mutableCopy];
__block NSMutableArray *tmpAssets = [@[] mutableCopy];
// 1

這是調用defaultAssetsLibrary方法，稍后您將看到

 ALAssetsLibrary *assetsLibrary = [ViewController defaultAssetsLibrary];
    // 2
    [assetsLibrary enumerateGroupsWithTypes:ALAssetsGroupAll usingBlock:^(ALAssetsGroup *group, BOOL *stop) {
        [group enumerateAssetsUsingBlock:^(ALAsset *result, NSUInteger index, BOOL *stop) {


  if(result)
            {

                // 3
                [tmpAssets addObject:result];
            }
        }];

        // 4
        //NSSortDescriptor *sort = [NSSortDescriptor sortDescriptorWithKey:@"date" ascending:NO];
        //self.assets = [tmpAssets sortedArrayUsingDescriptors:@[sort]];
        self.assets = tmpAssets;

        // 5
        [self.collectionView reloadData];
    } failureBlock:^(NSError *error) {
        NSLog(@"Error loading images %@", error);
    }];



}

- (void)didReceiveMemoryWarning
{
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}
#pragma mark - collection view data source


- (NSInteger) collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section
{
    return self.assets.count;
}

// The cell that is returned must be retrieved from a call to -dequeueReusableCellWithReuseIdentifier:forIndexPath:



- (MyCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath{
    MyCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:@"CELL" forIndexPath:indexPath];

    ALAsset *asset = self.assets[indexPath.row];
    cell.asset = asset;
    cell.backgroundColor = [UIColor redColor];
    ////
    //=


    cell.cellLabel.text = [NSString stringWithFormat:@"cell %i",indexPath.row];
    return cell;
}

- (void) collectionView:(UICollectionView *)collectionView didSelectItemAtIndexPath:(NSIndexPath *)indexPath
{
    ALAsset *asset = self.assets[indexPath.row];
    ALAssetRepresentation *defaultRep = [asset defaultRepresentation];
    UIImage *image = [UIImage imageWithCGImage:[defaultRep fullScreenImage] scale:[defaultRep scale] orientation:0];

    // Do something with the image

}

這是我認為返回照片庫的方法

+ (ALAssetsLibrary *)defaultAssetsLibrary
{


    static dispatch_once_t pred = 0;
    static ALAssetsLibrary *library = nil;
    dispatch_once(&pred, ^{
        library = [[ALAssetsLibrary alloc] init];
    });
    return library;
}

請幫助我從URL獲取圖像並將其顯示在圖像庫中。

就MyCell文件而言。

這是MYCell.m文件

@interface MyCell ()
// 1
@property(nonatomic, strong) IBOutlet UIImageView *photoImageView;
@end

@implementation MyCell

- (id)initWithFrame:(CGRect)frame
{
    self = [super initWithFrame:frame];
    if (self) {
        // Initialization code
    }
    return self;
}

- (void) setAsset:(ALAsset *)asset
{


    // 2
    _asset = asset;
    self.photoImageView.image = [UIImage imageWithCGImage:[asset thumbnail]];
    }

Answer 1

如果我們從URL獲取圖像，則實際上不需要AlAsset作為圖像庫。

我已經按照本教程制作了圖像庫Guide，並且Simple通過了url數組，並且對我有用。