前言
照片的选取在App中是相当普遍的场景，如用户修改头像、上传照片。一般给用户两种选择
1拍照
2从相册选取
在iOS中选择图片这个任务是通过UIImagePickerController来实现的，通过设置sourceType来决定是从相册选取还是拍照，当前的视图控制器需要实现UIImagePickerControllerDelegate协议的方法。
imagePickerController:didFinishPickingMediaWithInfo:
//用户选择了图片
imagePickerControllerDidCancel:
//用户取消选择
由于iOS系统的隐私保护机制，无论那种方式都必须先由用户授权否则我们没有权限，结果如下图
1，我们希望这个体验进行优化，2，这个场景很多，我们希望将其模块化,以便复用和拆封ViewController。我们这里只讨论选择一张图片的情况，多选照片的类库代码，现成类库比较多。
实现
综合来说我们的流程如下：1.弹出视图供用户选择一种方式；2.确定App是否有相应的权限，如果没有，提示用户没有权限并尝试引导用户去设置里面进行授权；3.选择照片返回。注意:UIActionSheet和UIAlertView在iOS9中已经废弃，提倡使用UIAlertController。考虑后期的复用、维护与完善，我们将其进行封装先定义一个ImagePickerModelDelegate协议，用来和视图控制器进行交互。
@protocol ImagePickerModelDelegate
-(void)imagePickerDidFinishWithImage:(UIImage)image;
-(void)imagePickerDidCancel;
//弹出警告框的视图
-(UIView)viewControllerView;
@end
新建NSObject的子类ImagePickerModel，并实现UIImagePickerControllerDelegate和UIActionSheetDelegate协议。声明两个方法
+(id)sharedInstance;
-(void)startShowSelectTypeViewWithViewController:(id)viewController andIsEdit:(BOOL)edit;
.m文件方法的实现
+(id)sharedInstance
{
if (!model)
{
model = [[ImagePickerModel alloc]init];
if([[UIDevice currentDevice]systemVersion]floatValue] >= 8.0)
{
isiOS8 = YES;
}
}
return model;
}
-(void)startShowSelectTypeViewWithViewController:(id)viewController andIsEdit:(BOOL)edit
{
isEdit = edit;
_delegate = viewController;
UIActionSheet *actSheet = [[UIActionSheet alloc]initWithTitle:nil delegate:self cancelButtonTitle:@"取消" destructiveButtonTitle:nil otherButtonTitles:@"相册",@"拍照", nil];
[actSheet showInView:[_delegate viewControllerView]];
[self takePicFromAlbum];
}
-(void)actionSheet:(UIActionSheet *)actionSheet
clickedButtonAtIndex:(NSInteger)buttonIndex
{
switch (buttonIndex)
{
case 0:
{
[self takePicFromAlbum];
break;
}
case 1:
{
[self takePicFromCamera];
break;
}
default:
break;
}
}```
无论那种操作之前，都先判断下权限
//从相册选取
- (void)takePicFromAlbum
{
ALAuthorizationStatus author = [ALAssetsLibrary authorizationStatus];
if (author == 1 || author == 2)
{
if(isiOS8)
{
UIAlertView *alertView = [[UIAlertView alloc]initWithTitle:@"警告" message:@"没有相册访问权限，请在设置-隐私-相册中进行设置！" delegate:self cancelButtonTitle:@"取消" otherButtonTitles:@"设置",nil];
}
else
{
UIAlertView *alertView = [[UIAlertView alloc]initWithTitle:@"警告" message:@"没有相册访问权限，请在设置-隐私-相册中进行设置！" delegate:nil cancelButtonTitle:@"取消" otherButtonTitles:nil];
}
[alertView show];
return;
}
UIImagePickerController pick = [[UIImagePickerController alloc] init];
pick.sourceType = UIImagePickerControllerSourceTypePhotoLibrary;
pick.delegate = self;
pick.allowsEditing = isEdit;
[(UIViewController)_delegate presentViewController:pick animated:YES completion:nil];
}
//从相机 - (void)takePicFromCamera
{
AVAuthorizationStatus authStatus = [AVCaptureDevice authorizationStatusForMediaType:AVMediaTypeVideo];
if (authStatus == AVAuthorizationStatusRestricted || authStatus ==AVAuthorizationStatusDenied)
{
if(isiOS8)
{
UIAlertView *alertView = [[UIAlertView alloc]initWithTitle:@"警告" message:@"没有相机访问权限，请在设置-隐私-相机中进行设置！" delegate:self cancelButtonTitle:@"取消" otherButtonTitles:@"设置",nil];
}
else
{
UIAlertView *alertView = [[UIAlertView alloc]initWithTitle:@"警告" message:@"没有相机访问权限，请在设置-隐私-相机中进行设置！" delegate:self cancelButtonTitle:@"取消" otherButtonTitles:@"设置",nil];
}
[alertView show];
return;
//无权限
}
if ([UIImagePickerController
isSourceTypeAvailable:UIImagePickerControllerSourceTypeCamera])
{
UIImagePickerController pick = [[UIImagePickerController alloc] init];
pick.sourceType = UIImagePickerControllerSourceTypeCamera;
pick.delegate = self;
pick.allowsEditing = isEdit;
[(UIViewController)_delegate presentViewController:pick animated:YES completion:nil];
}
else
{
NSLog(@"没有相机权限！");
}
}
-(void)alertView:(UIAlertView *)alertView clickedButtonAtIndex:(NSInteger)buttonIndex
{
//iOS8后允许打开系统设置
if (buttonIndex == 1)
{
[[UIApplication sharedApplication]openURL:[NSURL URLWithString:UIApplicationOpenSettingsURLString]];
}
}
选择或者取消后的操作
pragma mark - UIImagePickerController
- (void)imagePickerController:(UIImagePickerController *)picker
didFinishPickingMediaWithInfo:(NSDictionary *)info
{
UIImage *image = [info objectForKey:UIImagePickerControllerEditedImage];
if (!image)
{
image = [info objectForKey:UIImagePickerControllerOriginalImage];
}
[_delegate imagePickerDidFinishWithImage:image];
picker.delegate = nil;
[picker dismissViewControllerAnimated:YES completion:nil];
}
-(void)imagePickerControllerDidCancel:(UIImagePickerController *)picker
{
picker.delegate = nil;
[picker dismissViewControllerAnimated:YES completion:nil];
[_delegate imagePickerDidCancel];
}
