FirebaseDatabase Framework Reference

MutableData

classMutableData:NSObject

AMutableData instance is populated with data from a Firebase Database location. When you are usingrunTransactionBlock(_:), you will be given an instance containing the current data at that location. Your block will be responsible for updating that instance to the data you wish to save at that location, and then returning usingTransactionResult.success(withValue:).

To modify the data, set its value property to any of the Objective-C types supported by Firebase Database, or any equivalent natively bridgeable Swift type:

  • NSNumber (includes booleans)
  • NSDictionary
  • NSArray
  • NSString
  • nil /NSNull to remove the data

Note that changes made to a childMutableData instance will be visible to the parent.

  • Returns boolean indicating whether this mutable data has children.

    Declaration

    Swift

    funchasChildren()->Bool

    Return Value

    YES if this data contains child nodes.

  • Indicates whether this mutable data has a child at the given path.

    Declaration

    Swift

    funchasChild(atPathpath:String)->Bool

    Parameters

    path

    A path string, consisting either of a single segment, like‘child’, or multiple segments, ‘a/deeper/child’

    Return Value

    YES if this data contains a child at the specified relative path

  • Used to obtain aMutableData instance that encapsulates the data at the given relative path. Note that changes made to the child will be visible to the parent.

    Declaration

    Swift

    funcchildData(byAppendingPathpath:String)->MutableData

    Parameters

    path

    A path string, consisting either of a single segment, like‘child’, or multiple segments, ‘a/deeper/child’

    Return Value

    AMutableData instance containing the data at the given path

  • To modify the data contained by this instance ofMutableData, set this to any of the Objective-C types supported by Firebase Database, or any equivalent natively bridgeable Swift type:

    • NSNumber (includes booleans)
    • NSDictionary
    • NSArray
    • NSString
    • nil /NSNull to remove the data

    Note that setting this value will override the priority at this location.

    Declaration

    Swift

    varvalue:Any?{getset}

    Return Value

    The current data at this location as a native object

  • Set this property to update the priority of the data at this location. Can be set to any of the following Objective-C types supported by Firebase Database, or any equivalent natively bridgeable Swift type:

    • NSNumber (includes booleans)
    • NSString

    • nil /NSNull to remove the data

    Declaration

    Swift

    varpriority:Any?{getset}

    Return Value

    The priority of the data at this location

  • Declaration

    Swift

    varchildrenCount:UInt{get}

    Return Value

    The number of child nodes at this location

  • An enumeration of the children at this location.

    for var child in data.children { // … }

    Note that this enumerator operates on an immutable copy of the child list. So, you can modify the instance during iteration, but the new additions will not be visible until you get a new enumerator.

    Declaration

    Swift

    varchildren:NSEnumerator{get}

  • Declaration

    Swift

    varkey:String?{get}

    Return Value

    The key name of this node, ornil if it is the top-most location

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Last updated 2025-03-11 UTC.