Failed to start an Appium session using iPhone6, iOS8.4 simulator

This is my setup:

OS X Yosemite - 10.10.5
XCode - 7.2
iOS simulator - iPhone6(iOS 8.4)
Appium - 1.4.13

I launched Appium simulator then followed by launching Appium server(UI). I was trying to launch Appium inspector but getting following error.

My simulator is up and running, but still somehow session could not be established.
In-fact, I ran the command on command line that appium was trying to run, I see the same error. Can anyone help me, I am new to appium and unable to proceed with the following error.

Thanks in advance!!

info: --> POST /wd/hub/session {“desiredCapabilities”:{“platformName”:“iOS”,“platformVersion”:“8.4”,“newCommandTimeout”:“999999”,“automationName”:“Appium”,“deviceName”:“iPhone 6”}}
info: Client User-Agent string: Appium (unknown version) CFNetwork/720.5.7 Darwin/14.5.0 (x86_64)
info: *************************************
info: *************************************
info: *************************************
info: *************************************
info: *************************************
info: *************************************
info: *************************************
info: *************************************
info: **** NEW SESSION ***
info: **** NEW SESSION ***
info: **** NEW SESSION ***
info: **** NEW SESSION ***
info: **** NEW SESSION ***
info: **** NEW SESSION ***
info: **** NEW SESSION ***
info: **** NEW SESSION ***
info: *************************************
info: *************************************
info: *************************************
info: *************************************
info: *************************************
info: *************************************
info: *************************************
info: *************************************
info: [debug] Using local app from command line: /Users/sguntur/Downloads/UICatalog.app
info: [debug] Creating new appium session 8fc045b5-ef6a-4453-acb5-b9fc149e1bbf
info: [debug] Removing any remaining instruments sockets
info: [debug] Cleaned up instruments socket /tmp/instruments_sock
info: [debug] Auto-detecting iOS udid…
info: [debug] Not auto-detecting udid, running on sim

info: [debug] Parsed app Info.plist (as binary)
info: [debug] Parsed app Localizable.strings
info: [debug] Getting bundle ID from app
info: [debug] Parsed app Info.plist (as binary)
info: [debug] Creating instruments
info: [debug] Preparing uiauto bootstrap
info: [debug] Dynamic bootstrap dir: /Users/sguntur/Library/Application Support/appium/bootstrap
info: [debug] Dynamic env: {“nodePath”:"/Applications/Appium.app/Contents/Resources/node/bin/node",“commandProxyClientPath”:"/Applications/Appium.app/Contents/Resources/node_modules/appium/submodules/appium-uiauto/bin/command-proxy-client.js",“instrumentsSock”:"/tmp/instruments_sock",“interKeyDelay”:null,“justLoopInfinitely”:false,“autoAcceptAlerts”:false,“autoDismissAlerts”:false,“sendKeyStrategy”:“grouped”}
info: [debug] Dynamic bootstrap code: // This file is automatically generated. Do not manually modify!

info: [debug] Dynamic bootstrap path: /Users/sguntur/Library/Application Support/appium/bootstrap/bootstrap-5923cadea0343e3f.js
info: [debug] Reusing dynamic bootstrap: /Users/sguntur/Library/Application Support/appium/bootstrap/bootstrap-5923cadea0343e3f.js
info: [debug] Attempting iOS device log capture via libimobiledevice idevicesyslog

info: [debug] Creating iDevice object with udid 3770DAA9-A3F9-442F-B88B-94D57B3409F6

info: [debug] App is not installed. Will try to install the app.

error: Failed to start an Appium session, err was: Error: Command failed: /bin/sh -c ideviceinstaller -u 3770DAA9-A3F9-442F-B88B-94D57B3409F6 -i /Users/sguntur/Downloads/UICatalog.app

info: [debug] Cleaning up appium session
info: [debug] Error: Command failed: /bin/sh -c ideviceinstaller -u 3770DAA9-A3F9-442F-B88B-94D57B3409F6 -i /Users/sguntur/Downloads/UICatalog.app

at ChildProcess.exithandler (child_process.js:751:12)
at ChildProcess.emit (events.js:110:17)
at maybeClose (child_process.js:1015:16)
at Socket.<anonymous> (child_process.js:1183:11)
at Socket.emit (events.js:107:17)
at Pipe.close (net.js:485:12)

info: [debug] Responding to client with error: {“status”:33,“value”:{“message”:“A new session could not be created. (Original error: Command failed: /bin/sh -c ideviceinstaller -u 3770DAA9-A3F9-442F-B88B-94D57B3409F6 -i /Users/sguntur/Downloads/UICatalog.app\n)”,“killed”:false,“code”:2,“signal”:null,“cmd”:"/bin/sh -c ideviceinstaller -u 3770DAA9-A3F9-442F-B88B-94D57B3409F6 -i /Users/sguntur/Downloads/UICatalog.app",“origValue”:“Command failed: /bin/sh -c ideviceinstaller -u 3770DAA9-A3F9-442F-B88B-94D57B3409F6 -i /Users/sguntur/Downloads/UICatalog.app\n”},“sessionId”:null}
info: <-- POST /wd/hub/session 500 59.162 ms - 532

info: --> GET /wd/hub/status {}