Question

尝试按createdAt对快照数组进行排序。由于Google从“日期”格式更改为“时间戳记”，因此出现了困难

我尝试使用Timestamp.dateValue（）将时间戳转换为日期

当他们使用Date时，我使用了这个方法

 self.tableData = self.tableData.sorted(by: { 
 $0["createdAt"] as! Date > $1["createdAt"] as! Date })

我尝试将其与Timestamp一起使用，因为您无法直接在Timestamp上进行排序-我无法使其正常工作或语法不正确...

   self.tableData =  self.tableData.sorted(by: {
       $0["createdAt"] as Timestamp.dateValue() as! Date >
       $1["createdAt"] as Timestamp.dateValue() as! Date })

任何帮助将不胜感激。知道为什么Google从Date更改为Timestamp吗？这使排序更加困难。我知道您可以在请求期间进行排序，但是我需要根据数据库请求进行排序。

Answer 1

我这样做如下：-

在映射数据时，将其映射为日期类型变量：-

OBJECTS = $(SOURCES:$(SRC_PATH)/%.$(SRC_EXT)=$(BUILD_PATH)/%.o)
DEP = $(OBJECTS:.o=.d)

CPP_FLAGS = -std=c++11 -g -Wall -MD

.PHONY: default_target
default_target: release

.PHONY: release
release: dirs
    @$(MAKE) all

.PHONY: dirs
dirs:
    @echo "Creating directories"
    @mkdir -p $(dir $(OBJECTS))
    @mkdir -p $(BIN_PATH)

.PHONY: clean
clean:
    @echo "Deleting $(BIN_NAME) symlink"
    @$(RM) $(BIN_NAME)
    @echo "Deleting directories"
    @$(RM) -r $(BUILD_PATH)
    @$(RM) -r $(BIN_PATH)
    @$(RM) $(DEPS)

# checks the executable and symlinks to the output
.PHONY: all
all: $(BIN_PATH)/$(BIN_NAME)
    @echo "Making symlink: $(BIN_NAME) -> $<"
    @$(RM) $(BIN_NAME)
    @ln -s $(BIN_PATH)/$(BIN_NAME) $(BIN_NAME)

# Creation of the executable
$(BIN_PATH)/$(BIN_NAME): $(OBJECTS)
    @echo "Linking: $@"
    $(CXX) $(CPPFLAGS) $(LFLAGS) -o $@ $(OBJECTS) $(LIBS)

# Add dependency files, if they exist
-include $(DEPS)

# Source file rules
# After the first compilation they will be joined with the rules from the
# dependency files to provide header dependencies
$(BUILD_PATH)/%.o: $(SRC_PATH)/%.$(SRC_EXT)
    @echo "Compiling: $< -> $@"
    $(CXX) $(CPP_FLAGS) $(LFLAGS) -c $< -o $@ $(LIBS)

然后我对数组进行如下排序：-

let createdAt : Date? = snapshotValue["createdAt"] as? Date

OR

您可以直接获取排序的数据，如下所示：-

let currentArr = commentsArray.sorted(by: {
        $0.createdAt!.compare($1.createdAt!) == .orderedDescending
    })

Firebase createdAt-时间戳与日期

1 个答案: