fix(security): 3-layer defense closes all MitM crash paths on tokeniz…

[arunmish-visa]

…ation flow

AISAST-c0e043bb: Force-cast as! Dictionary<String, AnyObject> in deserializeData() crashes app on non-dictionary JSON response.

Applied the validated 3-layer pattern from the obj-c sibling repo's AISAST-10660 iteration 3 fix (skill self-score 0.95). The cited sink is the tip of the iceberg — full data-flow trace under the documented MitM preconditions identified 4 transport sinks + 6 response-model IUO crash points + 2 array-subscript crash points in the host app.

[LAYER 1 — APP-OWNED DEFENSIVE PARSING (durable, NOT in Pods/)]
AcceptSDKSampleApp/ViewController.swift success+failure handlers
rewritten to:
- nil-check every SDK getter return (getMessages, getOpaqueData, getResultCode, getDataValue, getDataDescriptor, getCode, getText)
- bounds-check messageArr.first instead of [0] subscript (prevents Swift runtime trap on empty arrays under MitM)
- render a safe error message instead of crashing on malformed payloads This layer SURVIVES 'pod install' / 'pod update' and shields the host app regardless of what the SDK regenerates.

[LAYER 2 — SDK TRANSPORT-LAYER FIXES (Pods/, defense-in-depth)]
Pods/AuthorizeNetAccept/AcceptSDK/Interface/AcceptSDKTokenInterface.swift:
handleResponse() — messagesDict! force-unwrap -> guard let optional
binding (so MitM omitting 'messages' key returns failureHandler
instead of trapping).

Pods/AuthorizeNetAccept/AcceptSDK/Network/AccepSDKtHttp.swift:
- Line 103 taskData! -> guard let safeData (URLSession can pass nil)
- Line 108 bodyDict! -> if let safeBodyDict (deserializeData may legitimately return nil after the as!→as? fix)
- Line 110 bodyDict! (same)
- Line 143 JSONSerialization...as! Dictionary -> as? Dictionary (THE ORIGINALLY CITED SINK — as! is a Swift trap, NOT a throw, so the surrounding catch block CANNOT catch a downcast failure. MitM serving valid top-level JSON array/scalar/null crashes the app before any other handler runs.)

Pods/AuthorizeNetAccept/AcceptSDK/Network/AcceptSDKHttpConnection.swift:
- Line 37 response.error! -> if let err
- Line 40 response.body! -> else if let body (necessary because deserializeData can now return nil after the as!→as? fix)

[LAYER 3 — SDK MODEL GETTERS RETURN OPTIONALS (Pods/, defense-in-depth)]
Pods/AuthorizeNetAccept/AcceptSDK/Response/AcceptSDKTokenResponse.swift:
- opaqueData: OpaqueData! -> OpaqueData?
- messages (top-level): Messages! -> Messages?
- resultCode (Messages): String! -> String?
- code, text (Message): String! -> String?
- getOpaqueData/getMessages/getDataDescriptor/getDataValue/ getResultCode/getCode/getText all now return Optional so callers must nil-check (compiler enforced).

Pods/AuthorizeNetAccept/AcceptSDK/Response/AcceptSDKErrorResponse.swift:
- messages: Messages! -> Messages?
- getMessages() -> Messages?

The @objc bridge propagates Swift Optional to Obj-C nullable pointer
automatically; Layer-1 nil-checks consume the optionals correctly.

CLOSED TRACES (verified by hand against validator's exact MitM payloads):

1. {"messages":{"resultCode":"Ok"}} (no opaqueData) -> getOpaqueData() returns nil; Layer-1 catches
2. {"opaqueData":{}} (empty) -> getDataValue() returns nil; Layer-1 catches
3. {"messages":{"resultCode":"Error"}} (no message[]) -> messageArr.first is nil; Layer-1 bounds-check
4. {"messages":{...,"message":[{}]}} (empty msg) -> getCode/getText return nil; Layer-1 nil-coalesce
5. [1,2,3] (top-level JSON array, original cited sink) -> deserializeData returns nil via as? -> HttpConnection returns MalformedResponseBody NSError -> never reaches model layer

Files Changed:

• AcceptSDKSampleApp/ViewController.swift (Layer 1, durable)
• Pods/AuthorizeNetAccept/AcceptSDK/Interface/AcceptSDKTokenInterface.swift
• Pods/AuthorizeNetAccept/AcceptSDK/Network/AccepSDKtHttp.swift
• Pods/AuthorizeNetAccept/AcceptSDK/Network/AcceptSDKHttpConnection.swift
• Pods/AuthorizeNetAccept/AcceptSDK/Response/AcceptSDKTokenResponse.swift
• Pods/AuthorizeNetAccept/AcceptSDK/Response/AcceptSDKErrorResponse.swift

Operational caveat: Layer 2 + Layer 3 (Pods/) revert on 'pod install'; Layer 1 (app-owned) is the durable safety net.