iOS之访问权限

从ios7开始，用户可以在设置->隐私->中开启或关闭某些系统权限，比如访问相册，相机 ，通讯录，地图，麦克风等。因此，在我们的程序中，如果要访问系统的某些功能，则最好判断一下权限是否开启。否则用户不能正常使用，也一头雾水，还以为程序出错了。

访问摄像头：

需要导入

#import <AVFoundation/AVFoundation.h>

if(isIOS7AndLater) {

NSString *mediaType = AVMediaTypeVideo;// Or AVMediaTypeAudio
AVAuthorizationStatus authStatus = [AVCaptureDevice authorizationStatusForMediaType:mediaType];
NSLog(@"---cui--authStatus--------%d",authStatus);
// This status is normally not visible—the AVCaptureDevice class methods for discovering devices do not return devices the user is restricted from accessing.
if(authStatus ==AVAuthorizationStatusRestricted){
NSLog(@"Restricted");
}else if(authStatus == AVAuthorizationStatusDenied){
// The user has explicitly denied permission for media capture.
NSLog(@"Denied");     //应该是这个，如果不允许的话
UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"提示"
message:@"请在设备的"设置-隐私-相机"中允许访问相机。"
delegate:self
cancelButtonTitle:@"确定"
otherButtonTitles:nil];
[alert show];
[alert release];
return;
}
else if(authStatus == AVAuthorizationStatusAuthorized){//允许访问
// The user has explicitly granted permission for media capture, or explicit user permission is not necessary for the media type in question.
NSLog(@"Authorized");

}else if(authStatus == AVAuthorizationStatusNotDetermined){
// Explicit user permission is required for media capture, but the user has not yet granted or denied such permission.
[AVCaptureDevice requestAccessForMediaType:mediaType completionHandler:^(BOOL granted) {
if(granted){//点击允许访问时调用
//用户明确许可与否，媒体需要捕获，但用户尚未授予或拒绝许可。
NSLog(@"Granted access to %@", mediaType);
}
else {
NSLog(@"Not granted access to %@", mediaType);
}

}];
}else {
NSLog(@"Unknown authorization status");
}
}

麦克风权限检测：

//检测麦克风功能是否打开
[[AVAudioSessionsharedInstance]requestRecordPermission:^(BOOL granted) {
if (!granted)
{
[ViewUtilalertViewWithString:NSLocalizedString(@"麦克风功能未开启",nil)];
}
else
{

[selfrecord:sender];
}
}];

相册权限检测：需要

#import <AssetsLibrary/AssetsLibrary.h> //导入此类和AssetsLibrary.framework框架

int author = [ALAssetsLibrary authorizationStatus];
NSLog(@"author type:%d",author);
if(author == ALAuthorizationStatusRestricted || author == ALAuthorizationStatusDenied) {
// The user has explicitly denied permission for media capture.
UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"无法使用相册"
message:@"请在iPhone的\"设置-隐私-照片\"中允许访问照片。"
delegate:self
cancelButtonTitle:@"确定"
otherButtonTitles:nil];
[alert show];
[alert release];
return;

ALAssetsLibrary详解

ALAssetsLibrary类是代表系统中整个资源库，使用它可以访问资源库中的资源和保存照片，视频等功能。

_library = [[ALAssetsLibrary alloc]init];

//判断当前应用是否能访问相册资源

/*

typedef NS_ENUM(NSInteger, ALAuthorizationStatus) {

ALAuthorizationStatusNotDetermined = 0, 用户尚未做出了选择这个应用程序的问候

ALAuthorizationStatusRestricted, 此应用程序没有被授权访问的照片数据。可能是家长控制权限。

ALAuthorizationStatusDenied, 用户已经明确否认了这一照片数据的应用程序访问.

ALAuthorizationStatusAuthorized 用户已授权应用访问照片数据.

}

*/

int author = [ALAssetsLibrary authorizationStatus];

NSLog(@"author type:%d",author);

//关闭监听共享照片流产生的频繁通知信息

[ALAssetsLibrary disableSharedPhotoStreamsSupport];

//创建一个相册到相册资源中，并通过block返回创建成功的相册ALAssetsGroup

[_library addAssetsGroupAlbumWithName:@"test" resultBlock:^(ALAssetsGroup *group) {

//NSString *const ALAssetsGroupPropertyName;

//NSString *const ALAssetsGroupPropertyType;

//NSString *const ALAssetsGroupPropertyPersistentID;

//NSString *const ALAssetsGroupPropertyURL;

//查看相册的名字

NSLog(@"ALAssetsGroupPropertyName:%@",[group valueForProperty:ALAssetsGroupPropertyName]);

//查看相册的类型

NSLog(@"ALAssetsGroupPropertyType:%@",[group valueForProperty:ALAssetsGroupPropertyType]);

//查看相册的存储id

NSLog(@"ALAssetsGroupPropertyPersistentID:%@",[group valueForProperty:ALAssetsGroupPropertyPersistentID]);

//查看相册存储的位置地址

NSLog(@"ALAssetsGroupPropertyURL:%@",[group valueForProperty:ALAssetsGroupPropertyURL]);

groupURL = [group valueForProperty:ALAssetsGroupPropertyURL];

} failureBlock:^(NSError *error) {

}];

新添加了一个名为test的相册

[NSThread sleepForTimeInterval:0.5];

//通过url地址在相册资源中获取该地址的资源文件ALAsset，有可能是相片或视频

[_library assetForURL:[NSURL URLWithString:@""] resultBlock:^(ALAsset *asset) {

/*

NSString *const ALAssetPropertyType;

NSString *const ALAssetPropertyLocation;

NSString *const ALAssetPropertyDuration;

NSString *const ALAssetPropertyOrientation;

NSString *const ALAssetPropertyDate;

NSString *const ALAssetPropertyRepresentations;

NSString *const ALAssetPropertyURLs;

NSString *const ALAssetPropertyAssetURL;

*/

//查看资源的地理位置信息

NSLog(@"ALAssetPropertyLocation:%@",[asset valueForProperty:ALAssetPropertyLocation]);

//如果资源是视频，查看视频的时长

NSLog(@"ALAssetPropertyDuration:%@",[asset valueForProperty:ALAssetPropertyDuration]);

//查看资源的方向，图片的旋转方向

NSLog(@"ALAssetPropertyOrientation:%@",[asset valueForProperty:ALAssetPropertyOrientation]);

//查看资源的创建时间

NSLog(@"ALAssetPropertyDate:%@",[asset valueForProperty:ALAssetPropertyDate]);

//查看资源的描述信息

NSLog(@"ALAssetPropertyRepresentations:%@",[asset valueForProperty:ALAssetPropertyRepresentations]);

NSLog(@"ALAssetPropertyURLs:%@",[asset valueForProperty:ALAssetPropertyURLs]);

//查看资源的url路径

NSLog(@"ALAssetPropertyAssetURL:%@",[asset valueForProperty:ALAssetPropertyAssetURL]);

} failureBlock:^(NSError *error) {

}];

//通过url地址获取相册资源中的一个相册

[_library groupForURL:groupURL resultBlock:^(ALAssetsGroup *group) {

NSLog(@"ALAssetsGroupPropertyName:%@",[group valueForProperty:ALAssetsGroupPropertyName]);

} failureBlock:^(NSError *error) {

}];

//根据选择的类型遍历相册资源中的相对应类型的所有相册，其中stop行参是指针，表示是否停止迭代，当赋值为false则停止

/*

enum {

ALAssetsGroupLibrary = (1 << 0),

ALAssetsGroupAlbum = (1 << 1),

ALAssetsGroupEvent = (1 << 2),

ALAssetsGroupFaces = (1 << 3),

ALAssetsGroupSavedPhotos = (1 << 4),

ALAssetsGroupPhotoStream = (1 << 5),

ALAssetsGroupAll = 0xFFFFFFFF,

};

*/

[_library enumerateGroupsWithTypes:ALAssetsGroupAll usingBlock:^(ALAssetsGroup *group, BOOL *stop) {

NSLog(@"group name:%@",[group valueForProperty:ALAssetsGroupPropertyName]);

} failureBlock:^(NSError *error) {

}];

//保存图片到系统默认的相册中，使用nsdata的形式，并返回照片的url地址

[_library writeImageDataToSavedPhotosAlbum:nil metadata:nil completionBlock:^(NSURL *assetURL, NSError *error) {

}];

//保存图片到系统默认的相册中，使用cgimageref的形式，并返回照片的url地址

[_library writeImageToSavedPhotosAlbum:nil metadata:nil completionBlock:^(NSURL *assetURL, NSError *error) {

}];

//保存图片到系统默认的相册中，使用cgimageref的形式，并且选择图片以什么旋转方向的形式保存，并返回照片的url地址

/*

typedef enum {

ALAssetOrientationUp, // default orientation

ALAssetOrientationDown, // 180 deg rotation

ALAssetOrientationLeft, // 90 deg CCW

ALAssetOrientationRight, // 90 deg CW

ALAssetOrientationUpMirrored, // as above but image mirrored along other axis. horizontal flip

ALAssetOrientationDownMirrored, // horizontal flip

ALAssetOrientationLeftMirrored, // vertical flip

ALAssetOrientationRightMirrored, // vertical flip

} ALAssetOrientation;

*/

UIImage* image = [UIImage imageNamed:@"test.png"];

[_library writeImageToSavedPhotosAlbum:[image CGImage] orientation:ALAssetOrientationLeft completionBlock:^(NSURL *assetURL, NSError *error) {

NSLog(@"save image:%@",assetURL);

}];