iOS：检测多媒体(相机、相册、麦克风)设备权限，弹框提示

一、感言

新年伊始，万象更新，一转眼，就2019年了。

作为一个科班生，从事移动端开发好几年了，回顾曾经的摸爬滚打，兢兢业业，严格的来说，多少算是入行了。

过去成绩如何暂且不说，新的一年，我当加倍努力，凤凰涅槃，浴火重生。

二、介绍

在项目中，多媒体的使用非常常见，那么，询问设备的权限必不可少。

优点：这么做极大的增强了用户体验，友好地告知用户去开启权限。

例如：相机的使用权限、相册的使用权限、麦克风的使用权限等

三、代码

1、相机的使用权限 （导入 #import <AVFoundation/AVFoundation.h>）

if (![UIImagePickerController isSourceTypeAvailable:UIImagePickerControllerSourceTypeCamera]){
     [self showAlertMessage:@"该设备不支持相机功能"];
     return;
}

AVAuthorizationStatus authStatus = [AVCaptureDevice authorizationStatusForMediaType:AVMediaTypeVideo];
if(authStatus == AVAuthorizationStatusRestricted || authStatus == AVAuthorizationStatusDenied){
     [self showAlertMessage:@"应用相机权限受限,请在设置中启用"];
     return;
 }

UIImagePickerController *picker = [[UIImagePickerController alloc] init];
picker.sourceType = UIImagePickerControllerSourceTypeCamera;
picker.delegate = self;
[self presentViewController:picker animated:YES completion:nil];

2、相册的使用权限（导入  #import<Photos/PHPhotoLibrary.h>）

if (![UIImagePickerController isSourceTypeAvailable:UIImagePickerControllerSourceTypePhotoLibrary]) {
     [self showAlertMessage:@"该设备不支持相册功能~"];
     return;
}

PHAuthorizationStatus status = [PHPhotoLibrary authorizationStatus];
if (status == PHAuthorizationStatusRestricted || status == PHAuthorizationStatusDenied){
    [self showAlertMessage:@"应用相册权限受限,请在设置中启用"];
    return;
}

UIImagePickerController *picker = [[UIImagePickerController alloc] init];
picker.sourceType = UIImagePickerControllerSourceTypePhotoLibrary;
picker.delegate = self;
[self presentViewController:picker animated:YES completion:nil];

3、麦克风的使用权限（导入 #import <AVFoundation/AVFoundation.h>）

AVAuthorizationStatus audioAuthStatus = [AVCaptureDevice authorizationStatusForMediaType:AVMediaTypeAudio];

if (audioAuthStatus == AVAuthorizationStatusNotDetermined) {  //未询问用户是否授权
    //第一次询问用户是否进行授权，只会调用一次
    [AVCaptureDevice requestAccessForMediaType:AVMediaTypeAudio completionHandler:^(BOOL granted) {
       if (!granted) {
          dispatch_async(dispatch_get_main_queue(), ^{ //手动禁止了授权
             [self showAlertMessage:@"您已禁用了麦克风，请到设置中开启后重试~"];
          });
        }
    }];
 }
 else if (audioAuthStatus == AVAuthorizationStatusAuthorized) { //麦克风已开启
     [[RecordUtility shareRecordUtility] startRecord]; //开始录音
 }
 else{ //未授权
     [self showAlertMessage:@"您未开启麦克风权限，请到设置中开启后重试~"];
 }

注意：跳转到设置中开启权限（CCBlcokAlertView是继承自UIAlertView的alertView，自己自定义一下吧，简单）

-(void)showAlertMessage:(NSString *)message{
    CCBlockAlertView *alertView = [[CCBlockAlertView alloc] initWithTitle:@"提示" message:message delegate:nil cancelButtonTitle:nil otherButtonTitles:@"确定", nil];
    alertView.delegate = alertView;
    alertView.blockAlertViewDidDismissWithButtonIndex = ^(CCBlockAlertView *blockAlertView, int buttonIndex) {
        if (buttonIndex == ) { // 点击了去设置,跳转设置
            NSURL *url = [NSURL URLWithString:UIApplicationOpenSettingsURLString];
            if ([[UIApplication sharedApplication] canOpenURL:url]) {
                [[UIApplication sharedApplication] openURL:url];
            }
        }
    };
    [alertView show];
}