苹果公司非常注重用户的隐私问题，所以在使用手机上一些涉及隐私的功能时，比如相册，相机，通讯录，录音权限等，需要征求用户的许可才可以使用。

一.权限状态说明

在使用相册，相机，通讯录，录音等功能时，我们需要通过不同的API获取到某一项功能的用户授权权限，用户授权的权限类型总结起来都可以归结为以下几种：

AuthorizationStatusNotDetermined      // 用户从未进行过授权等处理，首次访问相应内容会提示用户进行授权
AuthorizationStatusAuthorized = 0,    // 用户已授权，允许访问
AuthorizationStatusDenied,            // 用户拒绝访问
AuthorizationStatusRestricted,      //用户无法改编自合格权限，比如家长控制

二.具体的权限获取

1.相册权限获取

相册权限获取分三步：

• 设备是否支持
  在获取相册的权限之前，先要判断设备是否支持获取媒体资源，比如我想要挑选照片，但是现在相册中照片数量为0，那这时候就不能支持相册了：

[UIImagePickerController isSourceTypeAvailable:UIImagePickerControllerSourceTypePhotoLibrary]

typedef enum UIImagePickerControllerSourceType : NSInteger {
    UIImagePickerControllerSourceTypePhotoLibrary, //相册
    UIImagePickerControllerSourceTypeCamera,        //相机
    UIImagePickerControllerSourceTypeSavedPhotosAlbum
} UIImagePickerControllerSourceType;

• 获取相册权限状态
  如果第一步返回YES，也就是设备支持，那就可以获取目前的权限状态了：

PHAuthorizationStatus authStatus = [PHPhotoLibrary authorizationStatus];

权限状态有下列四种：

typedef enum PHAuthorizationStatus : NSInteger {
    PHAuthorizationStatusNotDetermined = 0,
    PHAuthorizationStatusRestricted,
    PHAuthorizationStatusDenied,
    PHAuthorizationStatusAuthorized
} PHAuthorizationStatus;

• 请求权限
  第二步中若status为PHAuthorizationStatusNotDetermined，也就是还没有请求过权限，那么就要请求权限：

[PHPhotoLibrary requestAuthorization:^(PHAuthorizationStatus status) {
        
    }];

2.相机权限获取

和相册权限一样，分三步：

• 设备是否支持：

[UIImagePickerController isSourceTypeAvailable:UIImagePickerControllerSourceTypeCamera]

• 获取相机权限状态
  如果第一步返回YES，那么就可以获取目前的权限状态：

AVAuthorizationStatus authStatus = [AVCaptureDevice authorizationStatusForMediaType:AVMediaTypeVideo];

权限状态有下列四种：

typedef enum AVAuthorizationStatus : NSInteger {
    AVAuthorizationStatusNotDetermined = 0,
    AVAuthorizationStatusRestricted = 1,
    AVAuthorizationStatusDenied = 2,
    AVAuthorizationStatusAuthorized = 3
} AVAuthorizationStatus;

• 请求权限

[AVCaptureDevice requestAccessForMediaType:AVMediaTypeVideo completionHandler:^(BOOL granted) {
        
    }];

3.通讯录权限获取

• 获取通讯录权限状态：

CNAuthorizationStatus status = [CNContactStore authorizationStatusForEntityType:CNEntityTypeContacts];

权限状态有四种：

typedef enum CNAuthorizationStatus : NSInteger {
    CNAuthorizationStatusNotDetermined = 0,
    CNAuthorizationStatusRestricted,
    CNAuthorizationStatusDenied,
    CNAuthorizationStatusAuthorized
} CNAuthorizationStatus;

• 请求权限

    CNContactStore *contact = [[CNContactStore alloc] init];
    [contact requestAccessForEntityType:CNEntityTypeContacts completionHandler:^(BOOL granted, NSError * _Nullable error) {
        
    }];

4.录音权限获取

• 获取录音权限状态：

    AVAudioSession *session = [AVAudioSession sharedInstance];
    AVAudioSessionRecordPermission permission = session.recordPermission;

权状态有三种：

typedef NS_ENUM(NSUInteger, AVAudioSessionRecordPermission)
{
    AVAudioSessionRecordPermissionUndetermined      = 'undt',
    AVAudioSessionRecordPermissionDenied            = 'deny',
    AVAudioSessionRecordPermissionGranted           = 'grnt'
};

• 请求权限

    AVAudioSession *session = [AVAudioSession sharedInstance];
    [session requestRecordPermission:^(BOOL granted) {
        
    }];

三.用户拒绝授权后的处理

用户拒绝授权后，再下次要使用相应的功能，可能会忘记自己之前已经拒绝了该授权，从而可能获取不到数据，这个时候应该给用户一个提示，提示用户去设置里面更改权限。
这里的给出了一种做法就是直接跳转到该应用的设置页面：

 NSURL *settingUrl = [NSURL URLWithString:UIApplicationOpenSettingsURLString];
  if ([[UIApplication sharedApplication] canOpenURL:settingUrl]) {
       [[UIApplication sharedApplication] openURL:settingUrl options:@{} completionHandler:^(BOOL success) {
            }];
        }

四.简单的封装

LMAuthorizationTool.h:

#import <Foundation/Foundation.h>

NS_ASSUME_NONNULL_BEGIN

typedef NS_ENUM(NSUInteger, LMAuthorizationStatus) {
    LMAuthorizationStatusAuthorized = 0, //用户已授权
    LMAuthorizationStatusDenied,         //拒绝
    LMAuthorizationStatusRestricted,     //应用没有相关权限，且当前用户无法改变这个权限，如家长控制
    LMAuthorizationStatusNotSupport      //硬件等不支持
};

typedef NS_ENUM(NSUInteger, LMMediaType) {
    LMMediaTypeAlbum = 0,    //相册
    LMMediaTypeCamera,       //相机
    LMMediaTypeAddressBook   //通讯录
};

@interface LMAuthorizationTool : NSObject

/**
 请求相册访问权限

 @param callback <callback description>
 */
+ (void)requestImagepickerAuthorization:(void(^)(LMAuthorizationStatus status))callback;


/**
 请求相机权限

 @param callback <callback description>
 */
+ (void)requestCameraAuthorization:(void(^)(LMAuthorizationStatus status))callback;


/**
 请求通讯录权限

 @param callback <callback description>
 */
+ (void)requestAddressBookAuthorization:(void(^)(LMAuthorizationStatus status))callback;


/**
 请求录音权限

 @param callback <callback description>
 */
+ (void)requestRecordAuthorization:(void(^)(LMAuthorizationStatus))callback;
@end

NS_ASSUME_NONNULL_END

LMAuthorizationTool.m

#import "LMAuthorizationTool.h"
#import <AssetsLibrary/AssetsLibrary.h>
#import <Photos/Photos.h>
#import <AddressBook/AddressBook.h>
#import <AddressBookUI/AddressBookUI.h>
#import <Contacts/Contacts.h>

@implementation LMAuthorizationTool
#pragma mark - 相册
+ (void)requestImagepickerAuthorization:(void (^)(LMAuthorizationStatus))callback
{

    //检查设备是否支持
    if ([UIImagePickerController isSourceTypeAvailable:UIImagePickerControllerSourceTypeCamera] || [UIImagePickerController isSourceTypeAvailable:UIImagePickerControllerSourceTypePhotoLibrary]) {
        
        PHAuthorizationStatus authStatus = [PHPhotoLibrary authorizationStatus];
        if (authStatus == PHAuthorizationStatusNotDetermined) {   //未授权
            [PHPhotoLibrary requestAuthorization:^(PHAuthorizationStatus status) {
                if (status == PHAuthorizationStatusAuthorized) {
                    [self executeCallback:callback status:LMAuthorizationStatusAuthorized];
                } else if (status == PHAuthorizationStatusDenied) {
                    [self executeCallback:callback status:LMAuthorizationStatusDenied];
                } else if (status == PHAuthorizationStatusRestricted) {
                    [self executeCallback:callback status:LMAuthorizationStatusRestricted];
                }
            }];
        } else if (authStatus == PHAuthorizationStatusAuthorized) {
            [self executeCallback:callback status:LMAuthorizationStatusAuthorized];
        } else if (authStatus == PHAuthorizationStatusDenied) {
            [self executeCallback:callback status:LMAuthorizationStatusDenied];
        } else if (authStatus == PHAuthorizationStatusRestricted) {
            [self executeCallback:callback status:LMAuthorizationStatusRestricted];
        }
    } else {
        [self executeCallback:callback status:LMAuthorizationStatusNotSupport];
    }
    
}
#pragma mark - 相机
+ (void)requestCameraAuthorization:(void (^)(LMAuthorizationStatus))callback
{
    if ([UIImagePickerController isSourceTypeAvailable:UIImagePickerControllerSourceTypeCamera]) {
        AVAuthorizationStatus authStatus = [AVCaptureDevice authorizationStatusForMediaType:AVMediaTypeVideo];
        if (authStatus == AVAuthorizationStatusNotDetermined) {
            [AVCaptureDevice requestAccessForMediaType:AVMediaTypeVideo completionHandler:^(BOOL granted) {
                if (granted) {
                    [self executeCallback:callback status:LMAuthorizationStatusAuthorized];
                } else {
                    [self executeCallback:callback status:LMAuthorizationStatusDenied];
                }
            }];
        } else if (authStatus == AVAuthorizationStatusAuthorized) {
            [self executeCallback:callback status:LMAuthorizationStatusAuthorized];
        } else if (authStatus == AVAuthorizationStatusDenied) {
            [self executeCallback:callback status:LMAuthorizationStatusDenied];
        } else if (authStatus == AVAuthorizationStatusRestricted) {
            [self executeCallback:callback status:LMAuthorizationStatusRestricted];
        }
    } else {
        [self executeCallback:callback status:LMAuthorizationStatusNotSupport];
    }
}

#pragma mark - 通讯录

+ (void)requestAddressBookAuthorization:(void (^)(LMAuthorizationStatus))callback
{
     CNAuthorizationStatus authStatus = [CNContactStore authorizationStatusForEntityType:CNEntityTypeContacts];
    if (authStatus == CNAuthorizationStatusNotDetermined) {
        CNContactStore *contactStore = [[CNContactStore alloc] init];
        [contactStore requestAccessForEntityType:CNEntityTypeContacts completionHandler:^(BOOL granted, NSError * _Nullable error) {
            if (granted) {
                [self executeCallback:callback status:LMAuthorizationStatusAuthorized];
            } else {
                [self executeCallback:callback status:LMAuthorizationStatusDenied];
            }
        }];
    } else if (authStatus == CNAuthorizationStatusAuthorized) {
        [self executeCallback:callback status:LMAuthorizationStatusAuthorized];
    } else if (authStatus == CNAuthorizationStatusDenied) {
        [self executeCallback:callback status:LMAuthorizationStatusDenied];
    } else if (authStatus == CNAuthorizationStatusRestricted) {
        [self executeCallback:callback status:LMAuthorizationStatusRestricted];
    }
}

#pragma mark - 录音
+ (void)requestRecordAuthorization:(void(^)(LMAuthorizationStatus))callback
{
    AVAudioSession *session = [AVAudioSession sharedInstance];
    AVAudioSessionRecordPermission permission = session.recordPermission;
    if (permission == AVAudioSessionRecordPermissionUndetermined) {
        [session requestRecordPermission:^(BOOL granted) {
            if (granted) {
                [self executeCallback:callback status:LMAuthorizationStatusAuthorized];
            } else {
                [self executeCallback:callback status:LMAuthorizationStatusDenied];
            }
        }];
    } else if (permission == AVAudioSessionRecordPermissionGranted) {
        [self executeCallback:callback status:LMAuthorizationStatusAuthorized];
    } else if (permission == AVAudioSessionRecordPermissionDenied) {
        [self executeCallback:callback status:LMAuthorizationStatusDenied];
    }
}

#pragma mark - callback
+ (void)executeCallback:(void (^)(LMAuthorizationStatus))callback status:(LMAuthorizationStatus)status
{
    dispatch_async(dispatch_get_main_queue(), ^{
        if (callback) {
            callback(status);
        }
    });
}

@end