# Image I/O Functions ## Topics ### Functions [`func CGImageDestinationAddImageAndMetadata(CGImageDestination, CGImage, CGImageMetadata?, CFDictionary?)`](/documentation/ImageIO/CGImageDestinationAddImageAndMetadata(_:_:_:_:)) [`func CGImageDestinationCopyImageSource(CGImageDestination, CGImageSource, CFDictionary?, UnsafeMutablePointer?>?) -> Bool`](/documentation/ImageIO/CGImageDestinationCopyImageSource(_:_:_:_:)) [`func CGImageSourceCopyMetadataAtIndex(CGImageSource, Int, CFDictionary?) -> CGImageMetadata?`](/documentation/ImageIO/CGImageSourceCopyMetadataAtIndex(_:_:_:)) [`func CGImageSourceRemoveCacheAtIndex(CGImageSource, Int)`](/documentation/ImageIO/CGImageSourceRemoveCacheAtIndex(_:_:)) [`func CGImageSourceSetAllowableTypes(CFArray) -> OSStatus`](/documentation/ImageIO/CGImageSourceSetAllowableTypes(_:)) Restricts which image formats can be decoded in the current process. --- Copyright © 2026 Apple Inc. All rights reserved. | [Terms of Use](https://www.apple.com/legal/internet-services/terms/site.html) | [Privacy Policy](https://www.apple.com/privacy/privacy-policy)