NSNumberFormatter显示10 ^ n（10000 - > 10k）的自定义标签

I need to display numbers on a plot axis. The values could change but I want to avoid too long numbers that will ruin the readability of the graph. My thought was to group every 3 characters and substitute them with K, M and so on (or a custom character). So: 1 -> 1, 999 -> 999, 1.000 -> 1k, 1.200 -> 1.2k, 1.280 -> 1.2k, 12.800 -> 12.8k, 999.999 -> 999.9k, 1.000.000 -> 1M, ...I need to display numbers on a plot axis. The v