翻译 Limit (aka AppMemoryLevel) is the maximum amount of memory you can use by through things like malloc, object allocations and so on (mostly heap)
限制（又名 AppMemoryLevel）是通过 malloc、对象分配等（主要是堆）可以使用的最大内存量
Pressure (aka AppMemoryPressure) is how much the iOS ecosystem is pushing on the current app to be a good memory citize 压力（又名 AppMemoryPressure）是指 iOS 生态系统对当前应用的内存占用压力
