NALU Type Array

NSString * const naluTypesStrings[] =
{
    @"0: Unspecified (non-VCL)",
    @"1: Coded slice of a non-IDR picture (VCL)",    // P frame
    @"2: Coded slice data partition A (VCL)",
    @"3: Coded slice data partition B (VCL)",
    @"4: Coded slice data partition C (VCL)",
    @"5: Coded slice of an IDR picture (VCL)",      // I frame
    @"6: Supplemental enhancement information (SEI) (non-VCL)",
    @"7: Sequence parameter set (non-VCL)",         // SPS parameter
    @"8: Picture parameter set (non-VCL)",          // PPS parameter
    @"9: Access unit delimiter (non-VCL)",
    @"10: End of sequence (non-VCL)",
    @"11: End of stream (non-VCL)",
    @"12: Filler data (non-VCL)",
    @"13: Sequence parameter set extension (non-VCL)",
    @"14: Prefix NAL unit (non-VCL)",
    @"15: Subset sequence parameter set (non-VCL)",
    @"16: Reserved (non-VCL)",
    @"17: Reserved (non-VCL)",
    @"18: Reserved (non-VCL)",
    @"19: Coded slice of an auxiliary coded picture without partitioning (non-VCL)",
    @"20: Coded slice extension (non-VCL)",
    @"21: Coded slice extension for depth view components (non-VCL)",
    @"22: Reserved (non-VCL)",
    @"23: Reserved (non-VCL)",
    @"24: STAP-A Single-time aggregation packet (non-VCL)",
    @"25: STAP-B Single-time aggregation packet (non-VCL)",
    @"26: MTAP16 Multi-time aggregation packet (non-VCL)",
    @"27: MTAP24 Multi-time aggregation packet (non-VCL)",
    @"28: FU-A Fragmentation unit (non-VCL)",
    @"29: FU-B Fragmentation unit (non-VCL)",
    @"30: Unspecified (non-VCL)",
    @"31: Unspecified (non-VCL)",
};

ref:here