iOS保存App中的照片到系统相册或自建相册的方法

保存照片到系统相册
保存照片到系统相册这个功能很多社交类的app都有的，今天我们简单讲解一下，如何将图片保存到系统相册（photo album）。

1.创建uiimageview

创建uiimageview是为了将照片展示出来，我们是要把uiimage保存到系统相册（photo album）:

#define screen [uiscreen mainscreen].bounds.size

self.image = [uiimage imagenamed:@"iosdevtip"];
uiimageview *imageview = [[uiimageview alloc] initwithframe:cgrectmake((screen.width - 300) / 2, 70, 300, 150)];
imageview.image = self.image;
[self.view addsubview:imageview];

2.创建uibutton

创建uibutton并绑定actionclick:事件:

uibutton *button = [[uibutton alloc] init];
button.frame = cgrectmake( 100, 300, screen.width - 200, 40);
[button addtarget:self action:@selector(actionclick:) forcontrolevents:uicontroleventtouchupinside];
[button settitlecolor:[uicolor bluecolor] forstate:uicontrolstatenormal];
[button setbackgroundcolor:[uicolor orangecolor]];
[button settitle:@"savephoto" forstate:uicontrolstatenormal];
[self.view addsubview:button];

- (void)actionclick:(uibutton *)button
{

}

3.保存照片到系统相册（photo album）

在actionclick:方法里调用：

uiimagewritetosavedphotosalbum(self.image, self, @selector(image:didfinishsavingwitherror:contextinfo:), null);

这个时候，我们想知道保存是否成功，所以需要制定回调方法

// 指定回调方法
- (void)image:(uiimage *)image didfinishsavingwitherror:(nserror *)error contextinfo:(void *)contextinfo
{
    if(!error){
        nslog(@"save success");
    }else{
        nslog(@"save failed");
    }
}

在这个方法里，我们就知道照片是否保存成功。

保存照片到自己创建的相簿

接下来，我们来详细讲解一下关于系统相册权限获取、保存照片、创建自己的相簿等等功能。

1.创建自己的相簿

这也是一种比较创建的作法，创建自己的相簿，然后把照片或者视频保存到自己的相簿中。相关代码如下：

  alassetslibrary *library = [[alassetslibrary alloc] init];
[library addassetsgroupalbumwithname:@"test" resultblock:^(alassetsgroup *group) {

    //创建相簿成功

} failureblock:^(nserror *error) {
    //失败
}];

2.保存照片

这个方法也是将照片保存到系统相簿里面，不是保存到自己创建的相簿里面。代码如下：

 alassetslibrary *library = [[alassetslibrary alloc]init];
[library writeimagetosavedphotosalbum:image.cgimage orientation:(alassetorientation)image.imageorientation completionblock:^(nsurl *asseturl,nserror *error){
    if (error) {
       //失败
    }else{
        uialertview *alert = [[uialertview alloc]initwithtitle:@"存储成功"
                                                       message:nil
                                                      delegate:nil
                                             cancelbuttontitle:@"确定"
                                             otherbuttontitles:nil, nil];
        [alert show];

    }
}];

3.获取权限
在保存照片之前，如果用户关闭相册权限，这个时候是保存失败的。如果你不做任何处理，用户是不会知道自己保存失败了。所以，我们可以在保存照片之前，做出相应的提示。如何获取这个权限呢？一般有两种方法：

（1）创建相簿失败

（2）保存照片失败

在上面两个方法创建自己的相簿和保存照片的失败结果里，我们可以弹出获取照片权限失败的提示。我们拿第一个创建相簿失败来举例：

alassetslibrary *library = [[alassetslibrary alloc] init];
[library addassetsgroupalbumwithname:@"test" resultblock:^(alassetsgroup *group)    {

      //创建相簿成功

} failureblock:^(nserror *error) {
    uialertview *alert = [[uialertview alloc]initwithtitle:@"存储失败"
                                                       message:@"请打开 设置-隐私-照片 来进行设置"
                                                      delegate:nil
                                             cancelbuttontitle:@"确定"
                                             otherbuttontitles:nil, nil];
    [alert show];
}];

在保存照片失败的结果里，我们也可以弹出相应的提示，让用户打开应用程序的相册权限。

4.保存照片到自己的相簿

下面这段代码是在大谷歌里面找到的，亲自测试过是可以用的，整理如下：

#pragma mark - 创建相册
- (void)createalbum
{
    alassetslibrary *assetslibrary = [[alassetslibrary alloc] init];
    nsmutablearray *groups=[[nsmutablearray alloc]init];
    alassetslibrarygroupsenumerationresultsblock listgroupblock = ^(alassetsgroup *group, bool *stop)
    {
        if (group)
        {
            [groups addobject:group];
        }

        else
        {
            bool havehdrgroup = no;

            for (alassetsgroup *gp in groups)
            {
                nsstring *name =[gp valueforproperty:alassetsgrouppropertyname];

                if ([name isequaltostring:@"iosdevtip"])
                {
                    havehdrgroup = yes;
                }
            }

            if (!havehdrgroup)
            {
                //do add a group named "xxxx"
                [assetslibrary addassetsgroupalbumwithname:@"iosdevtip"
                                               resultblock:^(alassetsgroup *group)
                 {
                     [groups addobject:group];

                 }
                                              failureblock:nil];
                havehdrgroup = yes;
            }
        }

    };
    //创建相簿
    [assetslibrary enumerategroupswithtypes:alassetsgroupalbum usingblock:listgroupblock failureblock:nil];

    [self savetoalbumwithmetadata:nil imagedata:uiimagepngrepresentation(self.image) customalbumname:@"iosdevtip" completionblock:^
     {
         //这里可以创建添加成功的方法

     }
                     failureblock:^(nserror *error)
     {
         //处理添加失败的方法显示alert让它回到主线程执行，不然那个框框死活不肯弹出来
         dispatch_async(dispatch_get_main_queue(), ^{

             //添加失败一般是由用户不允许应用访问相册造成的，这边可以取出这种情况加以判断一下
             if([error.localizeddescription rangeofstring:@"user denied access"].location != nsnotfound ||[error.localizeddescription rangeofstring:@"用户拒绝访问"].location!=nsnotfound){
                 uialertview *alert=[[uialertview alloc]initwithtitle:error.localizeddescription message:error.localizedfailurereason delegate:nil cancelbuttontitle:nslocalizedstring(@"ok", nil) otherbuttontitles: nil];

                 [alert show];
             }
         });
     }];
}

- (void)savetoalbumwithmetadata:(nsdictionary *)metadata
                      imagedata:(nsdata *)imagedata
                customalbumname:(nsstring *)customalbumname
                completionblock:(void (^)(void))completionblock
                   failureblock:(void (^)(nserror *error))failureblock
{

    alassetslibrary *assetslibrary = [[alassetslibrary alloc] init];
    __weak alassetslibrary *weakself = assetslibrary;
    void (^addasset)(alassetslibrary *, nsurl *) = ^(alassetslibrary *assetslibrary, nsurl *asseturl) {
        [assetslibrary assetforurl:asseturl resultblock:^(alasset *asset) {
            [assetslibrary enumerategroupswithtypes:alassetsgroupall usingblock:^(alassetsgroup *group, bool *stop) {

                if ([[group valueforproperty:alassetsgrouppropertyname] isequaltostring:customalbumname]) {
                    [group addasset:asset];
                    if (completionblock) {
                        completionblock();
                    }
                }
            } failureblock:^(nserror *error) {
                if (failureblock) {
                    failureblock(error);
                }
            }];
        } failureblock:^(nserror *error) {
            if (failureblock) {
                failureblock(error);
            }
        }];
    };
    [assetslibrary writeimagedatatosavedphotosalbum:imagedata metadata:metadata completionblock:^(nsurl *asseturl, nserror *error) {
        if (customalbumname) {
            [assetslibrary addassetsgroupalbumwithname:customalbumname resultblock:^(alassetsgroup *group) {
                if (group) {
                    [weakself assetforurl:asseturl resultblock:^(alasset *asset) {
                        [group addasset:asset];
                        if (completionblock) {
                            completionblock();
                        }
                    } failureblock:^(nserror *error) {
                        if (failureblock) {
                            failureblock(error);
                        }
                    }];
                } else {
                    addasset(weakself, asseturl);
                }
            } failureblock:^(nserror *error) {
                addasset(weakself, asseturl);
            }];
        } else {
            if (completionblock) {
                completionblock();
            }
        }
    }];
}