IOS进阶之AssetsLibrary.framework

AssetsLibrary.framework

官方文档

是用来访问手机用户的媒体数据的框架,这里的媒体数据是指手机照片应用的图片,视频,livephto等

只支持到IOS9.0 ,9.0以后官方推荐使用Photo.framework

主要的类

ALAsset

照片应用的图片,视频,livephto等实例

ALAssetsFilter

提供了对一组ALAsset的滤镜行为

ALAssetsGroup

一组ALAsset,与照片应用的顺序是一一对应的

ALAssetsLibrary

提供了访问照片应用里图片,video,或者livephoto的方法

ALAssetRepresentation

ALAsset的表示和说明,包括UTI,尺寸规格,文件大小,方向,缩放比例,文件名等等

<span style="font-size:14px;">self.assetsLibrary = [[ALAssetsLibrary alloc] init];    dispatch_queue_t dispatchQueue =dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);    dispatch_async(dispatchQueue, ^(void) {        // 遍历所有相册        [self.assetsLibrary enumerateGroupsWithTypes:ALAssetsGroupAll                                          usingBlock:^(ALAssetsGroup *group, BOOL *stop) {                                              // 遍历每个相册中的项ALAsset                                              [group enumerateAssetsUsingBlock:^(ALAsset *result, NSUInteger index,BOOL *stop) {                                                                                                     __block BOOL foundThePhoto = NO;                                                  if (foundThePhoto){                                                      *stop = YES;                                                  }                                                  // ALAsset的类型                                                  NSString *assetType = [result valueForProperty:ALAssetPropertyType];                                                  if ([assetType isEqualToString:ALAssetTypePhoto]){                                                      foundThePhoto = YES;                                                      *stop = YES;                                                      ALAssetRepresentation *assetRepresentation =[result defaultRepresentation];                                                      CGFloat imageScale = [assetRepresentation scale];                                                      UIImageOrientation imageOrientation = (UIImageOrientation)[assetRepresentation orientation];                                                      dispatch_async(dispatch_get_main_queue(), ^(void) {                                                          CGImageRef imageReference = [assetRepresentation fullResolutionImage];                                                          // 对找到的图片进行操作                                                          UIImage *image =[[UIImage alloc] initWithCGImage:imageReference scale:imageScale orientation:imageOrientation];                                                          if (image != nil){                                                              //获取到第一张图片                                                          } else {                                                              NSLog(@"Failed to create the image.");                                                          } });                                                  }                                              }];                                          }                                        failureBlock:^(NSError *error) {                                            NSLog(@"Failed to enumerate the asset groups.");                                        }];             });</span>

下面利用第三方框架

写一个选择多张图片的demo

ZYQAssetPickerController下载

#import "MainViewController.h"#import "ZYQAssetPickerController.h"#import "AppDelegate.h"@interface MainViewController ()<ZYQAssetPickerControllerDelegate,UINavigationControllerDelegate,UIScrollViewDelegate>{    UIButton *btn;        UIScrollView *src;        UIPageControl *pageControl;}@end@implementation MainViewController- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil{    self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];    if (self) {        // Custom initialization    }    return self;}- (void)viewDidLoad{    [super viewDidLoad];        btn=[[UIButton alloc] init];    btn.frame=CGRectMake(60., self.view.frame.size.height-80, self.view.frame.size.width-120, 60);    [btn setTitle:@"Open" forState:UIControlStateNormal];    [btn setTitleColor:[UIColor blackColor] forState:UIControlStateNormal];    [self.view addSubview:btn];    [btn addTarget:self action:@selector(btnClick:) forControlEvents:UIControlEventTouchUpInside];    src=[[UIScrollView alloc] initWithFrame:CGRectMake(20, 20, self.view.frame.size.width-40, self.view.frame.size.height-120)];    src.pagingEnabled=YES;    src.backgroundColor=[UIColor lightGrayColor];    src.delegate=self;    [self.view addSubview:src];        pageControl=[[UIPageControl alloc] initWithFrame:CGRectMake(src.frame.origin.x, src.frame.origin.y+src.frame.size.height-20, src.frame.size.width, 20)];    [self.view addSubview:pageControl];    }-(void)btnClick:(id)sender{     ZYQAssetPickerController *picker = [[ZYQAssetPickerController alloc] init];        picker.maximumNumberOfSelection = 9;    picker.assetsFilter = [ALAssetsFilter allPhotos];    picker.showEmptyGroups=NO;    picker.delegate=self;    picker.selectionFilter = [NSPredicate predicateWithBlock:^BOOL(id evaluatedObject, NSDictionary *bindings) {        if ([[(ALAsset*)evaluatedObject valueForProperty:ALAssetPropertyType] isEqual:ALAssetTypeVideo]) {            NSTimeInterval duration = [[(ALAsset*)evaluatedObject valueForProperty:ALAssetPropertyDuration] doubleValue];            return duration >= 5;        } else {            return YES;        }    }];        [self presentViewController:picker animated:YES completion:NULL];}- (void)didReceiveMemoryWarning{    [super didReceiveMemoryWarning];    // Dispose of any resources that can be recreated.}#pragma mark - ZYQAssetPickerController Delegate-(void)assetPickerController:(ZYQAssetPickerController *)picker didFinishPickingAssets:(NSArray *)assets{    [src.subviews makeObjectsPerformSelector:@selector(removeFromSuperview)];    dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{        src.contentSize=CGSizeMake(assets.count*src.frame.size.width, src.frame.size.height);        dispatch_async(dispatch_get_main_queue(), ^{            pageControl.numberOfPages=assets.count;        });        for (int i=0; i<assets.count; i++) {            ALAsset *asset=assets[i];            UIImageView *imgview=[[UIImageView alloc] initWithFrame:CGRectMake(i*src.frame.size.width, 0, src.frame.size.width, src.frame.size.height)];            imgview.contentMode=UIViewContentModeScaleAspectFill;            imgview.clipsToBounds=YES;            UIImage *tempImg=[UIImage imageWithCGImage:asset.defaultRepresentation.fullScreenImage];            dispatch_async(dispatch_get_main_queue(), ^{                [imgview setImage:tempImg];                [src addSubview:imgview];            });        }    });}#pragma mark - UIScrollView Delegate-(void)scrollViewDidScroll:(UIScrollView *)scrollView{    pageControl.currentPage=floor(scrollView.contentOffset.x/scrollView.frame.size.width);;}@end