Use this document as a guide when upgrading from LogKit 1 to LogKit 2. Although this document touches upon some of LogKit 2’s new features, it is meant more as a practical guide to getting up and running quickly rather than an exhaustive introduction to new features. Please refer to the ChangeLog or to the linked documentation to learn about what’s new in LogKit 2.

Initializing Endpoints

In the LogKit 2, the LXLogger object functions the same as in LogKit 1. However, many of the built-in Endpoints have updated initialization methods.

All Endpoints

The minimumLogLevel initialization parameter has been renamed to minimumPriorityLevel for all Endpoints.

The dateFormatter initialization parameter now requires an LXDateFormatter object for all Endpoints (see below).

The LXEntryFormatter object required for the entryFormatter initialization parameter has a new type (see below).

Console Endpoints

The Console and Serial Console Endpoints from LogKit 1 have both been replaced by a single Console Endpoint class called LXConsoleEndpoint. This new Endpoint includes all of the positive properties of each previous Endpoint. Developers may indicate whether they would like synchronous output (like the old Console Endpoint) or asynchronous output (like the old Serial Console Endpoint) using the synchronous parameter whilst initializing the Endpoint. Neither option allows text to overlap or become jumbled in LogKit 2.

File Endpoints

The LXLogFileEndpoint has been renamed LXFileEndpoint, and the LXLogDatedFileEndpoint has been renamed LXDatedFileEndpoint.

The File Endpoint includes a new initialization parameter shouldAppend that controls whether the log file will be appended to, or cleared upon initialization. Defaults to true if omitted.

The Dated File Endpoint’s initialization parameter fileURL has been renamed to baseURL to better reflect that the actual file URL will be modified (prepended with a datestamp).

LogKit 2 also includes a new Rotating File Endpoint, the LXRotatingFileEndpoint.

HTTP Endpoints

The LXLogHTTPEndpoint has been renamed LXHTTPEndpoint, and the LXLogHTTPJSONEndpoint has been renamed LXHTTPJSONEndpoint.

The HTTP and JSON Endpoints now cache pending uploads to persistent storage until the upload completes successfully. These Endpoints are now more resilient when faced with unreliable network conditions. Pending uploads will also persist between application runs, allowing LogKit to upload any remaining Entries at the next run time.

The HTTP and JSON Endpoints now accept an NSURLRequest as an initialization parameter. The request will be copied and used for all Log Entry uploads, allowing the developer more power in defining request parameters. The previous method of providing a URL and HTTP method is still supported as a convenience initializer, and in every case the developer can still provide an NSURLSessionConfiguration as well.

JSON Endpoint

The JSON Endpoint now uploads multiple Log Entries at once, when possible. Every upload from the JSON Endpoint now consists of a dictionary, with an array of Log Entries under the key entries.

The JSON Endpoint now formats dateTime properties using ISO 8601 date and time formatting
(yyyy-MM-dd'T'HH:mm:ss.SSSSSSZZZZZ) in the UTC timezone. In addition, the logLevel property of an LXLogEntry has been renamed level, and the JSON Endpoint honors this by uploading this property as level.

Finally, the JSON Endpoint has changed the way the userInfo property is included in Log Entry uploads. Instead of adding each of the dictionary’s key-value pairs as top-level items, the userInfo dictionary itself is included as a top-level value paired with the key userInfo.

An example of the LogKit 2 JSON Endpoint’s upload format, including all changes noted above:

    "entries": [
            "message": "Hello Internet!",
            "userInfo": {
                "my_property": 1,
                "other_property": 2,
            "dateTime": "2015-10-06T02:44:21.112000Z",
            "timestamp": 1444099461.112487,
            "level": "Debug",

Updating Custom Endpoints

Endpoints have changed slightly in LogKit 2, and custom Endpoints will need to be updated to reflect this.

The Endpoint Protocol

In LogKit 2, the LXLogEndpoint protocol has been renamed LXEndpoint. Additionally, the protocol’s minimumLogLevel property has been renamed minimumPriorityLevel. The dateFormatter and entryFormatter properties now require LXDateFormatter and LXEntryFormatter objects respectively, instead of the NSDateFormatter and entry formatting closures accepted in LogKit 1.

Finally, the protocol has picked up one additional property: requiresNewlines. This property should be either true or false depending on whether you want newline characters appended to each Log Entry before it is written to the Endpoint. For example, the included File Endpoint sets this property to true so that each Log Entry ends with a line break, but the included HTTP Endpoint sets this property to false, as there is no need to append newline characters to Entries being uploaded.

Priority Levels

The Priority Level enumeration LXLogLevel has been renamed LXPriorityLevel.

As mentioned above, the minimumLogLevel initialization parameter has been updated to minimumPriorityLevel for all included Endpoints.


LogKit 2 introduces some upgrades to the Log Entry formatting system.

Date Formatting

LogKit 2 introduces the LXDateFormatter object, replacing the NSDateFormatter previously used by Endpoints. LXDateFormatter is similar to NSDateFormatter, but is easier to initialize and includes a few built-in presets. LXDateFormatter uses the same date format strings as NSDateFormatter, so transitioning is simple. All Endpoints now require the use of an LXDateFormatter. See the formatting guide for full details.

// LogKit 1
let myDateFormatter: NSDateFormatter = {
    let formatter = NSDateFormatter()
    formatter.dateFormat = "yyyy-MM-dd HH:mm:ss.SSS"
    formatter.timeZone = NSTimeZone(forSecondsFromGMT: 0)
    return formatter

// LogKit 2 - defaults to UTC if timeZone: omitted
let myDateFormatter = LXDateFormatter(formatString: "yyyy-MM-dd HH:mm:ss.SSS", timeZone: NSTimeZone(forSecondsFromGMT: 0))

Entry Formatting

LogKit 2 upgrades the closure previously used to format Log Entries to an object of its own. The LXEntryFormatter object accepts the same closures used in LogKit 1 as its initialization parameter. LXEntryFormatter now includes a few built-in presets as well. All Endpoints require the use of an LXEntryFormatter. See the formatting guide for full details.

Any custom formatters using the Log Entry property logLevel should be updated to reflect that this property is now called level. In addition, several new properties have been made available, as described below.

// LogKit 1
let myEntryFormatter: LXLogEntryFormatter = { entry in return "[\(entry.logLevel)] \(entry.message)" }

// LogKit 2
let myEntryFormatter = LXEntryFormatter({ entry in return "[\(entry.level)] \(entry.message)" })

Log Entry Details

The Log Entry property logLevel has been renamed level.

Several new Log Entry properties have been made in LogKit 2. These include information on the device type, model, and operating system version of the device running an application, as well as the application’s bundle ID. Additionally, vendor and advertising IDs are available for devices that supply them.