Use file metadata with Cloud Storage on Apple platforms
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After uploading a file toCloud Storagereference, you can also get
and update the file metadata, for example to update the content type. Files
can also store custom key/value pairs with additional file metadata.
Get File Metadata
File metadata contains common properties such asname,size, andcontentType(often referred to as MIME type) in addition to some less
common ones likecontentDispositionandtimeCreated. This metadata can be
retrieved from aCloud Storagereference using
themetadataWithCompletion:method.
Swift
// Create reference to the file whose metadata we want to retrieveletforestRef=storageRef.child("images/forest.jpg")// Get metadata propertiesdo{letmetadata=tryawaitforestRef.getMetadata()}catch{// ...}
Objective-C
// Create reference to the file whose metadata we want to retrieveFIRStorageReference*forestRef=[storageRefchild:@"images/forest.jpg"];// Get metadata properties[forestRefmetadataWithCompletion:^(FIRStorageMetadata*metadata,NSError*error){if(error!=nil){// Uh-oh, an error occurred!}else{// Metadata now contains the metadata for 'images/forest.jpg'}}];
Update File Metadata
You can update file metadata at any time after the file upload completes by
using theupdateMetadata:withCompletion:method. Refer to thefull listfor more information on what properties
can be updated. Only the properties specified in the metadata are updated,
all others are left unmodified.
Swift
// Create reference to the file whose metadata we want to changeletforestRef=storageRef.child("images/forest.jpg")// Create file metadata to updateletnewMetadata=StorageMetadata()newMetadata.cacheControl="public,max-age=300"newMetadata.contentType="image/jpeg"// Update metadata propertiesdo{letupdatedMetadata=tryawaitforestRef.updateMetadata(newMetadata)}catch{// ...}
Objective-C
// Create reference to the file whose metadata we want to changeFIRStorageReference*forestRef=[storageRefchild:@"images/forest.jpg"];// Create file metadata to updateFIRStorageMetadata*newMetadata=[[FIRStorageMetadataalloc]init];newMetadata.cacheControl=@"public,max-age=300";newMetadata.contentType=@"image/jpeg";// Update metadata properties[forestRefupdateMetadata:newMetadatacompletion:^(FIRStorageMetadata*metadata,NSError*error){if(error!=nil){// Uh-oh, an error occurred!}else{// Updated metadata for 'images/forest.jpg' is returned}}];
You can delete writable metadata properties by setting them tonil:
Objective-C
FIRStorageMetadata*newMetadata=[[FIRStorageMetadataalloc]init];newMetadata.contentType=nil;// Delete the metadata property[forestRefupdateMetadata:newMetadatacompletion:^(FIRStorageMetadata*metadata,NSError*error){if(error!=nil){// Uh-oh, an error occurred!}else{// metadata.contentType should be nil}}];
Swift
letnewMetadata=StorageMetadata()newMetadata.contentType=nildo{// Delete the metadata propertyletupdatedMetadata=tryawaitforestRef.updateMetadata(newMetadata)}catch{// ...}
Handle Errors
There are a number of reasons why errors may occur on getting or updating
metadata, including the file not existing, or the user not having permission
to access the desired file. More information on errors can be found in theHandle Errorssection of the docs.
Custom Metadata
You can specify custom metadata as anNSDictionarycontainingNSStringproperties.
Swift
letmetadata=["customMetadata":["location":"Yosemite, CA, USA","activity":"Hiking"]]
Objective-C
NSDictionary*metadata=@{@"customMetadata":@{@"location":@"Yosemite, CA, USA",@"activity":@"Hiking"}};
You can store app-specific data for each file in custom metadata, but we highly
recommend using a database (such as theFirebase Realtime Database) to store and synchronize this type of
data.
File Metadata Properties
A full list of metadata properties on a file is available below:
Property
Type
Writable
bucket
String
No
generation
String
No
metageneration
String
No
fullPath
String
No
name
String
No
size
Int64
No
timeCreated
Date
No
updated
Date
No
md5Hash
String
Yes
cacheControl
String
Yes
contentDisposition
String
Yes
contentEncoding
String
Yes
contentLanguage
String
Yes
contentType
String
Yes
customMetadata
[String: String]
Yes
Uploading, downloading, and updating files is important, but so is being able
to remove them. Let's learn how todelete filesfromCloud Storage.
[[["Easy to understand","easyToUnderstand","thumb-up"],["Solved my problem","solvedMyProblem","thumb-up"],["Other","otherUp","thumb-up"]],[["Missing the information I need","missingTheInformationINeed","thumb-down"],["Too complicated / too many steps","tooComplicatedTooManySteps","thumb-down"],["Out of date","outOfDate","thumb-down"],["Samples / code issue","samplesCodeIssue","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-09-04 UTC."],[],[],null,["\u003cbr /\u003e\n\nAfter uploading a file to Cloud Storage reference, you can also get\nand update the file metadata, for example to update the content type. Files\ncan also store custom key/value pairs with additional file metadata.\n| **Note:** By default, a Cloud Storage for Firebase bucket requires Firebase Authentication to perform any action on the bucket's data or files. You can change your Firebase Security Rules for Cloud Storage to [allow unauthenticated access for specific situations](/docs/storage/security/rules-conditions#public). However, for most situations, we strongly recommend [restricting access and setting up robust security rules](/docs/storage/security/get-started) (especially for production apps). Note that if you use Google App Engine and have a default Cloud Storage bucket with a name format of `*.appspot.com`, you may need to consider [how your security rules impact access to App Engine files](/docs/storage/gcp-integration#security-rules-and-app-engine-files).\n\nGet File Metadata\n\nFile metadata contains common properties such as `name`, `size`, and\n`contentType` (often referred to as MIME type) in addition to some less\ncommon ones like `contentDisposition` and `timeCreated`. This metadata can be\nretrieved from a Cloud Storage reference using\nthe `metadataWithCompletion:` method. \n\nSwift \n\n```swift\n// Create reference to the file whose metadata we want to retrieve\nlet forestRef = storageRef.child(\"images/forest.jpg\")\n\n// Get metadata properties\ndo {\n let metadata = try await forestRef.getMetadata()\n} catch {\n // ...\n}\n \n```\n\nObjective-C \n\n```objective-c\n// Create reference to the file whose metadata we want to retrieve\nFIRStorageReference *forestRef = [storageRef child:@\"images/forest.jpg\"];\n\n// Get metadata properties\n[forestRef metadataWithCompletion:^(FIRStorageMetadata *metadata, NSError *error) {\n if (error != nil) {\n // Uh-oh, an error occurred!\n } else {\n // Metadata now contains the metadata for 'images/forest.jpg'\n }\n}];\n \n```\n\nUpdate File Metadata\n\nYou can update file metadata at any time after the file upload completes by\nusing the `updateMetadata:withCompletion:` method. Refer to the\n[full list](#file_metadata_properties) for more information on what properties\ncan be updated. Only the properties specified in the metadata are updated,\nall others are left unmodified. \n\nSwift \n\n```swift\n// Create reference to the file whose metadata we want to change\nlet forestRef = storageRef.child(\"images/forest.jpg\")\n\n// Create file metadata to update\nlet newMetadata = StorageMetadata()\nnewMetadata.cacheControl = \"public,max-age=300\"\nnewMetadata.contentType = \"image/jpeg\"\n\n// Update metadata properties\ndo {\n let updatedMetadata = try await forestRef.updateMetadata(newMetadata)\n} catch {\n // ...\n}\n \n```\n\nObjective-C \n\n```objective-c\n// Create reference to the file whose metadata we want to change\nFIRStorageReference *forestRef = [storageRef child:@\"images/forest.jpg\"];\n\n// Create file metadata to update\nFIRStorageMetadata *newMetadata = [[FIRStorageMetadata alloc] init];\nnewMetadata.cacheControl = @\"public,max-age=300\";\nnewMetadata.contentType = @\"image/jpeg\";\n\n// Update metadata properties\n[forestRef updateMetadata:newMetadata completion:^(FIRStorageMetadata *metadata, NSError *error){\n if (error != nil) {\n // Uh-oh, an error occurred!\n } else {\n // Updated metadata for 'images/forest.jpg' is returned\n }\n}];\n \n```\n\nYou can delete writable metadata properties by setting them to `nil`: \n\nObjective-C \n\n```objective-c\nFIRStorageMetadata *newMetadata = [[FIRStorageMetadata alloc] init];\nnewMetadata.contentType = nil;\n\n// Delete the metadata property\n[forestRef updateMetadata:newMetadata completion:^(FIRStorageMetadata *metadata, NSError *error){\n if (error != nil) {\n // Uh-oh, an error occurred!\n } else {\n // metadata.contentType should be nil\n }\n}];\n```\n\nSwift \n\n```swift\nlet newMetadata = StorageMetadata()\nnewMetadata.contentType = nil\n\ndo {\n // Delete the metadata property\n let updatedMetadata = try await forestRef.updateMetadata(newMetadata)\n} catch {\n // ...\n}\n```\n\nHandle Errors\n\nThere are a number of reasons why errors may occur on getting or updating\nmetadata, including the file not existing, or the user not having permission\nto access the desired file. More information on errors can be found in the\n[Handle Errors](/docs/storage/ios/handle-errors)\nsection of the docs.\n\nCustom Metadata\n\nYou can specify custom metadata as an `NSDictionary` containing `NSString`\nproperties. \n\nSwift \n\n```swift\nlet metadata = [\n \"customMetadata\": [\n \"location\": \"Yosemite, CA, USA\",\n \"activity\": \"Hiking\"\n ]\n]\n \n```\n\nObjective-C \n\n```objective-c\nNSDictionary *metadata = @{\n @\"customMetadata\": @{\n @\"location\": @\"Yosemite, CA, USA\",\n @\"activity\": @\"Hiking\"\n }\n};\n```\n\nYou can store app-specific data for each file in custom metadata, but we highly\nrecommend using a database (such as the\n[Firebase Realtime Database](/docs/database)) to store and synchronize this type of\ndata.\n\nFile Metadata Properties\n\nA full list of metadata properties on a file is available below:\n\n| Property | Type | Writable |\n|----------------------|--------------------|----------|\n| `bucket` | String | No |\n| `generation` | String | No |\n| `metageneration` | String | No |\n| `fullPath` | String | No |\n| `name` | String | No |\n| `size` | Int64 | No |\n| `timeCreated` | Date | No |\n| `updated` | Date | No |\n| `md5Hash` | String | Yes |\n| `cacheControl` | String | Yes |\n| `contentDisposition` | String | Yes |\n| `contentEncoding` | String | Yes |\n| `contentLanguage` | String | Yes |\n| `contentType` | String | Yes |\n| `customMetadata` | \\[String: String\\] | Yes |\n\n| **Note:** at present, setting the `md5Hash` property on upload doesn't affect the upload, as hash verification is not yet implemented.\n\nUploading, downloading, and updating files is important, but so is being able\nto remove them. Let's learn how to\n[delete files](/docs/storage/ios/delete-files)\nfrom Cloud Storage."]]
