調用系統圖片庫以及攝像頭

判斷當前設備是否有攝像頭

if ([UIImagePickerController isSourceTypeAvailable:UIImagePickerControllerSourceTypeCamera]) 

創建UIAlertController選擇

- (void)openLocalPhoto
{
     UIAlertController *alertController = [UIAlertController alertControllerWithTitle:@"獲取圖片" message:@"請選擇方式" preferredStyle:UIAlertControllerStyleActionSheet];
    
     UIAlertAction *defaultAction = [UIAlertAction actionWithTitle:@"拍照" style:UIAlertActionStyleDefault handler:^(UIAlertAction * _Nonnull action) {
            UIImagePickerController *imagePikerController = [[UIImagePickerController alloc]init];
            imagePikerController.delegate = self;
            imagePikerController.allowsEditing = YES;
            imagePikerController.sourceType = UIImagePickerControllerSourceTypeCamera;
            MYLog(@"相機");
            [self presentViewController:imagePikerController animated:YES completion:nil];
        }];

    UIAlertAction *defaultAction1 = [UIAlertAction actionWithTitle:@"從相冊獲取" style:UIAlertActionStyleDefault handler:^(UIAlertAction * _Nonnull action) {
        UIImagePickerController *imagePickerController = [[UIImagePickerController alloc]init];
        imagePickerController.delegate = self;
        imagePickerController.allowsEditing = YES;
        imagePickerController.sourceType = UIImagePickerControllerSourceTypePhotoLibrary;
        MYLog(@"相冊");
        [self presentViewController:imagePickerController animated:YES completion:nil];
    }];
    UIAlertAction *cancelAction = [UIAlertAction actionWithTitle:@"取消" style:UIAlertActionStyleCancel handler:^(UIAlertAction * _Nonnull action) {
        MYLog(@"取消");
    }];
    
    [alertController addAction:defaultAction];
    [alertController addAction:cancelAction];
    [alertController addAction:defaultAction1];
    
    [self presentViewController:alertController animated:YES completion:nil];
    
}```

###以下是使用相機技術需要遵守的兩個協議方法

_<UIImagePickerControllerDelegate,UINavigationControllerDelegate>_

點擊完成后怎么做

• (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary<NSString *,id> *)info
  {
  UIImage *image = info[UIImagePickerControllerEditedImage];
  self.headerImageView.image = image;
  [self dismissViewControllerAnimated:picker completion:nil];
  }```
  點擊取消按鈕怎么做

-(void)imagePickerControllerDidCancel:(UIImagePickerController *)picker{
    [picker dismissViewControllerAnimated:YES completion:nil];
}```

###iOS 8.0以前使用的方法
遵守四個協議

_<UIImagePickerControllerDelegate,UINavigationControllerDelegate,UIActionSheetDelegate,UIAlertViewDelegate>_

-(void)open{
UIActionSheet *sht = [[UIActionSheet alloc]initWithTitle:@"請選擇"
delegate:self
cancelButtonTitle:@"取消"
destructiveButtonTitle:@"相機"
otherButtonTitles:@"相冊", nil];
}```

-(void)actionSheet:(UIActionSheet *)actionSheet clickedButtonAtIndex:(NSInteger)buttonIndex{
    if (buttonIndex == 2) {
        MYLog(@"取消");
    }else if (buttonIndex == 1){
        MYLog(@"相冊");
        UIImagePickerController *imagePicker = [UIImagePickerController new];
        imagePicker.delegate = self;
        imagePicker.sourceType = UIImagePickerControllerSourceTypePhotoLibrary;
        imagePicker.allowsEditing = YES;
        [self presentViewController:imagePicker animated:YES completion:nil];
    }else{
        MYLog(@"相機");
        if ([UIImagePickerController isSourceTypeAvailable:UIImagePickerControllerSourceTypeCamera]) {
            UIImagePickerController *imagePicker = [UIImagePickerController new];
            imagePicker.delegate = self;
            imagePicker.sourceType = UIImagePickerControllerSourceTypePhotoLibrary;
            imagePicker.allowsEditing = YES;
            [self presentViewController:imagePicker animated:YES completion:nil];
        }else{
            MYLog(@"無法識別到相機");
        }
    }
}```

##壓縮照片技術

• (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary<NSString ,id> )info
  {
  UIImage image = info[UIImagePickerControllerOriginalImage];
  MYLog(@"image length = %ld",UIImagePNGRepresentation(image).length);//原圖
  / 縮略圖/
  UIImage *newImage = [self thumnailWithImage:image size:CGSizeMake(100, 100)];
  MYLog(@"newImage length = %ld",UIImagePNGRepresentation(newImage).length);

  /** 發送數據 二次壓縮圖*/
  NSData *sendData = UIImageJPEGRepresentation(newImage, 0.05);//參數越高 質量越好0-1
  MYLog(@"sendData length = %ld",sendData.length);
  [self realSendImageMsg:sendData];

  [self dismissViewControllerAnimated:picker completion:nil];
  }```
  ** 生成縮略圖**

-(UIImage *)thumnailWithImage:(UIImage *)image size:(CGSize)size{
    UIImage *newImage = nil;
    if (image != nil) {
        UIGraphicsBeginImageContext(size);
        
        [image drawInRect:CGRectMake(0, 0, size.width, size.height)];
        newImage = UIGraphicsGetImageFromCurrentImageContext();

        UIGraphicsEndImageContext();
    }
    return newImage;
}```
** 發送圖片消息**

-(void)realSendImageMsg:(NSData *)data{
//把data 轉成文本 base64編碼
NSString *base64Str = [data base64EncodedStringWithOptions:0];
//構建圖片消息對象
XMPPMessage *msg = [XMPPMessage messageWithType:@"chat" to:self.friendJid];
[msg addBody:base64Str];
//發送消息
[[KRXmppTool sharedKRXmppTool].xmppStream sendElement:msg];
}```

-(void)imagePickerControllerDidCancel:(UIImagePickerController *)picker{
    [picker dismissViewControllerAnimated:YES completion:nil];
}