FirebaseDatabase Framework Reference

FIRDataSnapshot

@interface FIRDataSnapshot : NSObject

A DataSnapshot contains data from a Firebase Database location. Any time you read Firebase data, you receive the data as a DataSnapshot.

DataSnapshots are passed to the blocks you attach with observe(_:with:) or observeSingleEvent(of:with:). They are efficiently-generated immutable copies of the data at a Firebase Database location. They can’t be modified and will never change. To modify data at a location, use a DatabaseReference (e.g. with setValue(_:)).

Navigating and inspecting a snapshot

• -childSnapshotForPath:

  Gets a DataSnapshot for the location at the specified relative path. The relative path can either be a simple child key (e.g. ‘fred’) or a deeper slash-separated path (e.g. ‘fred/name/first’). If the child location has no data, an empty DataSnapshot is returned.

  Declaration

  Objective-C

  - (nonnull FIRDataSnapshot *)childSnapshotForPath:
      (nonnull NSString *)childPathString;

  Parameters

  childPathString

  A relative path to the location of child data.

  Return Value

  The DataSnapshot for the child location.

• -hasChild:

  Return true if the specified child exists.

  Declaration

  Objective-C

  - (BOOL)hasChild:(nonnull NSString *)childPathString;

  Parameters

  childPathString

  A relative path to the location of a potential child.

  Return Value

  true if data exists at the specified childPathString, else false.

• -hasChildren

  Return true if the DataSnapshot has any children.

  Declaration

  Objective-C

  - (BOOL)hasChildren;

  Return Value

  true if this snapshot has any children, else false.

• -exists

  Return true if the DataSnapshot contains a non-null value.

  Declaration

  Objective-C

  - (BOOL)exists;

  Return Value

  true if this snapshot contains a non-null value, else false.

Data export

• -valueInExportFormat

  Returns the raw value at this location, coupled with any metadata, such as priority.

  Priorities, where they exist, are accessible under the “.priority” key in instances of NSDictionary. For leaf locations with priorities, the value will be under the “.value” key.

  Declaration

  Objective-C

  - (id _Nullable)valueInExportFormat;

Properties

• value

  Returns the contents of this data snapshot as native types.

  Data types returned:

  • Dictionary
  • Array
  • NSNumber-bridgeable types, including Bool

  • String

  Declaration

  Objective-C

  @property (nonatomic, strong, readonly, nullable) id value;

  Return Value

  The data as a native object.

• childrenCount

  Gets the number of children for this DataSnapshot.

  Declaration

  Objective-C

  @property (nonatomic, readonly) NSUInteger childrenCount;

  Return Value

  An integer indicating the number of children.

• ref

  Gets a DatabaseReference for the location that this data came from.

  Declaration

  Objective-C

  @property (nonatomic, strong, readonly) FIRDatabaseReference *_Nonnull ref;

  Return Value

  A DatabaseReference instance for the location of this data.

• key

  The key of the location that generated this DataSnapshot.

  Declaration

  Objective-C

  @property (nonatomic, strong, readonly) NSString *_Nonnull key;

  Return Value

  A String containing the key for the location of this DataSnapshot.

• children

  An iterator for snapshots of the child nodes in this snapshot.

   for var child in snapshot.children {
     // ...
   }
  

  Declaration

  Objective-C

  @property (nonatomic, strong, readonly) NSEnumerator<FIRDataSnapshot *> *_Nonnull children;

  Return Value

  An NSEnumerator of the children.

• priority

  The priority of the data in this DataSnapshot.

  Declaration

  Objective-C

  @property (nonatomic, strong, readonly, nullable) id priority;

  Return Value

  The priority as a String, or nil if no priority was set.