好些天没写点东西了，最近公司要做新项目，有点小忙。不想我的坚持就此中断，我把我前些天研究的东西拿出来给大家看看。
这次整理的是assetslibrary和photokit的使用。本人处女座，有点强迫症，之前写的项目里用的是assetslibrary写的调取相册内的媒体文件，但是xcode总是报警告错误，虽然能够编译并展示效果，但是十几个警告错误挂在那，心里总不是滋味，所以我就研究了一下assetlibrary和photokit。
在 ios 8 出现之前，开发者只能使用 assetslibrary 框架来访问设备的照片库，这是一个有点跟不上 ios 应用发展步伐以及代码设计原则但确实强大的框架，考虑到 ios7 仍占有不少的渗透率，因此 assetslibrary 也是本文重点介绍的部分。而在 ios8 出现之后，苹果提供了一个名为 photokit 的框架，一个可以让应用更好地与设备照片库对接的框架。
一、assetslibrary 组成
assetslibrary 的组成比较符合照片库本身的组成，照片库中的完整照片库对象、相册、相片都能在 assetslibrary 中找到一一对应的组成，这使到 assetslibrary 的使用变得直观而方便。想要了解assetslibrary得从它的类开始。
assetslibrary: 代表整个设备中的资源库（照片库），通过 assetslibrary 可以获取和包括设备中的照片和视频
@话不多说,直接上代码
我要评论
#import <assetslibrary/assetslibrary.h> // 必须导入
// 照片原图路径
#define koriginalphotoimagepath \
[[nssearchpathfordirectoriesindomains(nscachesdirectory, nsuserdomainmask, yes) objectatindex:0] stringbyappendingpathcomponent:@"originalphotoimages"]
// 视频url路径
#define kvideourlpath \
[[nssearchpathfordirectoriesindomains(nscachesdirectory, nsuserdomainmask, yes) objectatindex:0] stringbyappendingpathcomponent:@"videourl"]
// caches路径
#define kcachespath \
[nssearchpathfordirectoriesindomains(nscachesdirectory, nsuserdomainmask, yes) objectatindex:0]
// mainviewcontroller
@interface mthmainviewcontroller ()
@property (nonatomic,strong) mthnextviewcontroller *nextvc;
@property (nonatomic,strong) nsmutablearray *grouparrays;
@property (nonatomic,strong) uiimageview *litimgview;
@end
@implementation mthmainviewcontroller
- (id)initwithnibname:(nsstring *)nibnameornil bundle:(nsbundle *)nibbundleornil
{
self = [super initwithnibname:nibnameornil bundle:nibbundleornil];
if (self) {
// custom initialization
}
return self;
}
- (void)viewdidload
{
[super viewdidload];
// do any additional setup after loading the view.
self.navigationitem.title = @"demo";
self.view.backgroundcolor = [uicolor clearcolor];
// 初始化
self.grouparrays = [nsmutablearray array];
// 测试baritem
self.navigationitem.rightbarbuttonitem = [[uibarbuttonitem alloc] initwithtitle:@"测试" style:uibarbuttonitemstyleplain target:self action:@selector(testrun)];
// 测试手势
uipangesturerecognizer *panrecognizer = [[uipangesturerecognizer alloc] initwithtarget:self action:@selector(didclickpangesturerecognizer:)];
[self.navigationcontroller.view addgesturerecognizer:panrecognizer];
// 图片或者视频的缩略图显示
self.litimgview = [[uiimageview alloc] initwithframe:cgrectmake(100, 200, 120, 120)];
[self.view addsubview:_litimgview];
}
- (void)testrun
{
__weak mthmainviewcontroller *weakself = self;
dispatch_async(dispatch_get_global_queue(dispatch_queue_priority_default, 0), ^{
alassetslibrarygroupsenumerationresultsblock listgroupblock = ^(alassetsgroup *group, boolbool *stop) {
if (group != nil) {
[weakself.grouparrays addobject:group];
} else {
[weakself.grouparrays enumerateobjectsusingblock:^(id obj, nsuinteger idx, boolbool *stop) {
[obj enumerateassetsusingblock:^(alasset *result, nsuinteger index, boolbool *stop) {
if ([result thumbnail] != nil) {
// 照片
if ([[result valueforproperty:alassetpropertytype] isequaltostring:alassettypephoto]){
nsdate *date= [result valueforproperty:alassetpropertydate];
uiimage *image = [uiimage imagewithcgimage:[result thumbnail]];
nsstring *filename = [[result defaultrepresentation] filename];
nsurl *url = [[result defaultrepresentation] url];
int64_t filesize = [[result defaultrepresentation] size];
nslog(@"date = %@",date);
nslog(@"filename = %@",filename);
nslog(@"url = %@",url);
nslog(@"filesize = %lld",filesize);
// ui的更新记得放在主线程,要不然等子线程排队过来都不知道什么年代了,会很慢的
dispatch_async(dispatch_get_main_queue(), ^{
self.litimgview.image = image;
});
}
// 视频
else if ([[result valueforproperty:alassetpropertytype] isequaltostring:alassettypevideo] ){
// 和图片方法类似
}
}
}];
}];
}
};
alassetslibraryaccessfailureblock failureblock = ^(nserror *error)
{
nsstring *errormessage = nil;
switch ([error code]) {
case alassetslibraryaccessuserdeniederror:
case alassetslibraryaccessgloballydeniederror:
errormessage = @"用户拒绝访问相册,请在<隐私>中开启";
break;
default:
errormessage = @"reason unknown.";
break;
}
dispatch_async(dispatch_get_main_queue(), ^{
uialertview *alertview = [[uialertview alloc]initwithtitle:@"错误,无法访问!"
message:errormessage
delegate:self
cancelbuttontitle:@"确定"
otherbuttontitles:nil, nil nil];
[alertview show];
});
};
alassetslibrary *assetslibrary = [[alassetslibrary alloc] init];
[assetslibrary enumerategroupswithtypes:alassetsgroupall
usingblock:listgroupblock failureblock:failureblock];
});
}
@但是:
按照上面方法直接取出来的路径是无法传输的,必须自己转化成nsdata对象重新写入沙盒路径
// 将原始图片的url转化为nsdata数据,写入沙盒
- (void)imagewithurl:(nsurl *)url withfilename:(nsstring *)filename
{
// 进这个方法的时候也应该加判断,如果已经转化了的就不要调用这个方法了
// 如何判断已经转化了,通过是否存在文件路径
alassetslibrary *assetlibrary = [[alassetslibrary alloc] init];
// 创建存放原始图的文件夹--->originalphotoimages
nsfilemanager * filemanager = [nsfilemanager defaultmanager];
if (![filemanager fileexistsatpath:koriginalphotoimagepath]) {
[filemanager createdirectoryatpath:koriginalphotoimagepath withintermediatedirectories:yes attributes:nil error:nil];
}
dispatch_async(dispatch_get_global_queue(dispatch_queue_priority_default, 0), ^{
if (url) {
// 主要方法
[assetlibrary assetforurl:url resultblock:^(alasset *asset) {
alassetrepresentation *rep = [asset defaultrepresentation];
byte *buffer = (byte*)malloc((unsigned long)rep.size);
nsuinteger buffered = [rep getbytes:buffer fromoffset:0.0 length:((unsigned long)rep.size) error:nil];
nsdata *data = [nsdata datawithbytesnocopy:buffer length:buffered freewhendone:yes];
nsstring * imagepath = [koriginalphotoimagepath stringbyappendingpathcomponent:filename];
[data writetofile:imagepath atomically:yes];
} failureblock:nil];
}
});
}
// 将原始视频的url转化为nsdata数据,写入沙盒
- (void)videowithurl:(nsurl *)url withfilename:(nsstring *)filename
{
// 解析一下,为什么视频不像图片一样一次性开辟本身大小的内存写入?
// 想想,如果1个视频有1g多,难道直接开辟1g多的空间大小来写?
alassetslibrary *assetlibrary = [[alassetslibrary alloc] init];
dispatch_async(dispatch_get_global_queue(dispatch_queue_priority_default, 0), ^{
if (url) {
[assetlibrary assetforurl:url resultblock:^(alasset *asset) {
alassetrepresentation *rep = [asset defaultrepresentation];
nsstring * videopath = [kcachespath stringbyappendingpathcomponent:filename];
char constconst *cvideopath = [videopath utf8string];
filefile *file = fopen(cvideopath, "a+");
if (file) {
const int buffersize = 11024 * 1024;
// 初始化一个1m的buffer
byte *buffer = (byte*)malloc(buffersize);
nsuinteger read = 0, offset = 0, written = 0;
nserror* err = nil;
if (rep.size != 0)
{
do {
read = [rep getbytes:buffer fromoffset:offset length:buffersize error:&err];
written = fwrite(buffer, sizeof(char), read, file);
offset += read;
} while (read != 0 && !err);//没到结尾，没出错，ok继续
}
// 释放缓冲区，关闭文件
free(buffer);
buffer = null;
fclose(file);
file = null;
}
} failureblock:nil];
}
});
}
以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持移动技术网。
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