Let's identify some ICs on the front side of the logic board:
with text background colors.
Apple A8 APL1011 SoC + Elpida 1 GB LPDDR3 RAM (as denoted by the markings EDF8164A3PM-GD-F)
Qualcomm MDM9625M LTE Modem
Skyworks 77802-23 Low Band LTE PAD
Avago A8020 High Band PAD
Avago A8010 Ultra High Band PA + FBARs
TriQuint TQF6410 3G EDGE Power Amplifier Module
InvenSense MP67B 6-axis Gyroscope and Accelerometer Combo
More ICs on the front of the logic board:
Qualcomm QFE1000 Envelope Tracking IC
RF Micro Devices RF5159 Antenna Switch Module
SkyWorks 77356-8 Mid Band PAD
Back of the logic board.
SK Hynix H2JTDG8UD1BMS 128 Gb (16 GB) NAND Flash
Murata 339S0228 Wi-Fi Module
Apple/Dialog 338S1251-AZ Power Management IC
Broadcom BCM5976 Touchscreen Controller
NXP LPC18B1UK ARM Cortex-M3 Microcontroller (also known as the M8 motion coprocessor)
NXP 65V10 NFC module + Secure Element (likely contains an NXP PN544 NFC controller inside)
Qualcomm WTR1625L RF Transceiver
More ICs on the back of the logic board:
Qualcomm WFR1620 receive-only companion chip. Qualcomm states that the WFR1620 is "required for implementation of carrier aggregation with WTR1625L."
Qualcomm PM8019 Power Management IC
Texas Instruments 343S0694 Touch Transmitter
AMS AS3923 NFC Booster IC
Cirrus Logic 338S1201 Audio Codec