Question

我有一个iOS应用程序，有时需要在本地存储UIImage对象。

我使用[UIImagePNGRepresentation(image) writeToFile:full_path options:NSAtomicWrite error:nil];保存图片，[file_manager removeItemAtPath:full_path error:NULL];删除文件。

这一切都很好，但是，每当我删除一个文件时，我是否应该决定保存一个新文件（恰好与旧文件同名），保存代码不起作用，返回以下错误：

：ImageIO：CGImageReadCreateDataWithMappedFile＆＃39; open＆＃39;失败   error = 2（没有这样的文件或目录）

：ImageIO：CGImageReadCreateDataWithMappedFile＆＃39; open＆＃39;失败   error = 2（没有这样的文件或目录）

：ImageIO：PNG zlib错误

因此，我删除旧文件后，为什么我不能保存与旧文件同名的文件？

我问这个的原因是，我的应用程序将保存某些图像文件，然后当不再需要它们时，我的应用程序将删除它们。但是，有时我的应用程序需要再次使用图像文件（可能是删除后几个小时或几周）。发生这种情况时，我的应用程序将加载适当的图像数据，然后尝试保存它。那就是错误发生的时候。

这里出了什么问题？

谢谢你的时间，Dan。

更新 - 以下是我设置的用于保存/访问和删除图像文件的方法

-(void)save_local_image:(UIImage *)image :(NSString *)file_name {

    // Get the app documents directory link.
    NSString *documents = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) objectAtIndex:0];

    // Add the new file name to the link.
    NSString *database_link = [[NSString alloc] initWithString:[documents stringByAppendingPathComponent:file_name]];

    // Save the image data locally.
    [UIImagePNGRepresentation(image) writeToFile:database_link options:NSAtomicWrite error:nil];
}

-(UIImage *)get_local_image:(NSString *)file_name {

    // Create the return data.
    UIImage *image_data = nil;

    // Get the app documents directory.
    NSArray *directory = [[NSFileManager defaultManager] contentsOfDirectoryAtPath:[NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) lastObject] error:NULL];

    // Only check for data if at least
    // one file has been saved locally.

    if ([directory count] > 0) {

        // Loop through the different local files.

        for (NSString *path in directory) {

            // Get the full local file URL.
            NSString *full_path = [[NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) lastObject] stringByAppendingPathComponent:path];

            // Get the range of the file name.
            NSRange range = [full_path rangeOfString:file_name];

            // Get the image data if it exists.

            if ((range.location != NSNotFound) || (range.length == [file_name length])) {

                // Load the image file in.
                image_data = [UIImage imageWithContentsOfFile:full_path];

                break;
            }
        }
    }

    return image_data;
}

-(void)delete_local_image:(NSString *)file_name {

    // Get the app documents directory.
    NSArray *directory = [[NSFileManager defaultManager] contentsOfDirectoryAtPath:[NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) lastObject] error:NULL];

    // Only check for data if at least
    // one file has been saved locally.

    if ([directory count] > 0) {

        // Loop through the different local files.

        for (NSString *path in directory) {

            // Get the full local file URL.
            NSString *full_path = [[NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) lastObject] stringByAppendingPathComponent:path];

            // Get the range of the file name.
            NSRange range = [full_path rangeOfString:file_name];

            // Delete the local image data if it exists.

            if ((range.location != NSNotFound) || (range.length == [file_name length])) {

                NSError *testError = nil;

                // Delete the image file.
                NSFileManager *file_manager = [[NSFileManager alloc] init];
                BOOL success = [file_manager removeItemAtPath:full_path error:&testError];

                NSLog(@"%d", success);

                if (testError != nil) {
                    NSLog(@"%@", testError.localizedDescription);
                }


                break;
            }
        }
    }
}

Answer 1

我用它来保存并阅读：

const initialState = {
  graphDatas: [],
  friendsList : {},
  comments: []
}

function addData(state = initialState.graphDatas, action) {
  switch(action.type) {
    case 'RECIEVE_DATA':
      var clone = _.cloneDeep(state);
      var resultPopOff = clone.pop()
      let stateResult = _.isEqual(resultPopOff, action.data)
      if (stateResult) {
        return state
      } else {
        return [
          ...state, action.data
        ]
      }
    default:
      return state;
  }
}

const payment = (state = initialState, action) => {
  switch(action.type) {
    default:
      return {
        graphDatas: addData(state.graphDatas, action)
      }
  }
}

const rootReducer = combineReducers({
  payment, routing: routerReducer
})

export default rootReducer

removeItemAtPath后writeToFile不起作用

1 个答案: