Adds rate limit to APIProvider

[mathiasemil]

APIProvider now exposes rate limit information from the X-Rate-Limit header field.

public let rateLimitPublisher = PassthroughSubject<RateLimit, Never>()

Rate limits are included in the header for every response and are enforced for all requests using the same API Key.

The documentation defines that the header info includes:

• user-hour-lim, which indicates the number of requests you can make per hour with the same API key.
• user-hour-rem, which shows the number of requests remaining.
  https://developer.apple.com/documentation/appstoreconnectapi/identifying_rate_limits

However certain endpoints will also include user-minute-lim and user-minute-rem. I have filed a feedback to ask that this is added to the documentation.
Since this solution does not make assumptions about which entries are included in X-Rate-Limit this should not be an issue.

Usage

let cancellable = apiProvider.rateLimitPublisher.sink { rateLimit in
    if let remaining = rateLimit.entries["user-hour-rem"], let limit = rateLimit.entries["user-hour-lim"] {
        print("Rate limit: \(remaining)/\(limit)")
    }
}

Per endpoint limits
Rate limits apply to all requests, but it appears it is possible for certain endpoints have their own limits. Because of this I have added requestURL to RateLimit so you're able to see rate limits for specific endpoints.

[SwiftLeeBot]

	Warnings
⚠️	'Prices' is deprecated: Deprecated
⚠️	'AvailableTerritories' is deprecated: Deprecated
⚠️	'InAppPurchases' is deprecated: Deprecated
⚠️	'Prices' is deprecated: Deprecated
⚠️	'AvailableTerritories' is deprecated: Deprecated
⚠️	'InAppPurchases' is deprecated: Deprecated
⚠️	'AppPrice' is deprecated: Deprecated
⚠️	'AgeRatingDeclaration' is deprecated: Deprecated
⚠️	'AgeRatingDeclaration' is deprecated: Deprecated
⚠️	'AppStoreVersionSubmission' is deprecated: Deprecated
⚠️	'AppStoreVersionSubmission' is deprecated: Deprecated
⚠️	'Prices' is deprecated: Deprecated
⚠️	'AvailableTerritories' is deprecated: Deprecated
⚠️	'Prices' is deprecated: Deprecated
⚠️	'AvailableTerritories' is deprecated: Deprecated
⚠️	'AppPrice' is deprecated: Deprecated
⚠️	'Prices' is deprecated: Deprecated
⚠️	'AvailableTerritories' is deprecated: Deprecated
⚠️	'InAppPurchases' is deprecated: Deprecated
⚠️	'AppPrice' is deprecated: Deprecated
⚠️	'AgeRatingDeclaration' is deprecated: Deprecated
⚠️	'AppStoreVersionSubmission' is deprecated: Deprecated
⚠️	'AppStoreVersionSubmission' is deprecated: Deprecated
⚠️	'Prices' is deprecated: Deprecated
⚠️	'AvailableTerritories' is deprecated: Deprecated
⚠️	'AppPrice' is deprecated: Deprecated

	Messages
📖	AppStoreConnect-Swift-SDK-Tests: Executed 16 tests (0 failed, 0 retried, 0 skipped) in 0.067 seconds
📖	View more details on Bitrise

Code Coverage Report

Name	Coverage

SwiftLint found issues

Severity	File	Reason
Warning	RateLimit.swift:13	Lines should not have trailing whitespace. (trailing_whitespace)
Warning	RateLimit.swift:16	Lines should not have trailing whitespace. (trailing_whitespace)
Warning	RateLimit.swift:19	Lines should not have trailing whitespace. (trailing_whitespace)
Error	RateLimitTests.swift:41	Line should be 160 characters or less: currently 215 characters (line_length)
Warning	RateLimitTests.swift:9	Imports should be sorted. (sorted_imports)
Warning	RateLimitTests.swift:19	Lines should not have trailing whitespace. (trailing_whitespace)
Warning	RateLimitTests.swift:24	Lines should not have trailing whitespace. (trailing_whitespace)
Warning	RateLimitTests.swift:30	Lines should not have trailing whitespace. (trailing_whitespace)
Warning	RateLimitTests.swift:39	Lines should not have trailing whitespace. (trailing_whitespace)
Warning	DefaultRequestExecutor.swift:67	Line should be 140 characters or less: currently 153 characters (line_length)
Warning	DefaultRequestExecutor.swift:86	Line should be 140 characters or less: currently 156 characters (line_length)
Warning	DefaultRequestExecutor.swift:35	Chained function calls should be either on the same line, or one per line. (multiline_function_chains)
Warning	DefaultRequestExecutor.swift:46	Chained function calls should be either on the same line, or one per line. (multiline_function_chains)
Warning	DefaultRequestExecutor.swift:60	Use shorthand syntax for optional binding (shorthand_optional_binding)
Warning	DefaultRequestExecutor.swift:79	Use shorthand syntax for optional binding (shorthand_optional_binding)
Warning	APIProvider.swift:73	Use shorthand syntax for optional binding (shorthand_optional_binding)
Warning	APIProvider.swift:9	Imports should be sorted. (sorted_imports)
Warning	APIProvider.swift:135	Lines should not have trailing whitespace. (trailing_whitespace)
Warning	APIProvider.swift:241	Lines should not have trailing whitespace. (trailing_whitespace)
Warning	APIProvider.swift:271	Lines should not have trailing whitespace. (trailing_whitespace)
Warning	APIProvider.swift:292	Lines should not have trailing whitespace. (trailing_whitespace)
Warning	APIProvider.swift:309	Lines should not have trailing whitespace. (trailing_whitespace)
Warning	APIProvider.swift:319	Lines should not have trailing whitespace. (trailing_whitespace)
Warning	APIProvider.swift:335	Lines should not have trailing whitespace. (trailing_whitespace)
Warning	APIProvider.swift:348	Lines should not have trailing whitespace. (trailing_whitespace)
Warning	APIProvider.swift:359	Lines should not have trailing whitespace. (trailing_whitespace)
Warning	APIProvider.swift:369	Lines should not have trailing whitespace. (trailing_whitespace)
Warning	APIProvider.swift:377	Lines should not have trailing whitespace. (trailing_whitespace)
Warning	APIProvider.swift:103	Parentheses are not needed when declaring closure arguments. (unneeded_parentheses_in_closure_argument)
Warning	APIProviderTests.swift:43	Method 'setUp()' should call to super function (overridden_super_call)
Warning	APIProviderTests.swift:9	Imports should be sorted. (sorted_imports)

Generated by 🚫 Danger Swift against ae3af97

[mathiasemil]

It turns out there was a case sensitivity issue when looking up the rate limit header field name. Apparently Proxyman uppercases all header field names and since the API returns lowercased field names the solution only worked when Proxyman was running🤦‍♂️

I changed the solution to use value(forHTTPHeaderField:) which ensures header field names are case-insensitive.

[AvdLee]

Looks really good, you made it easy to review. Thanks for writing some tests as well!