ios - 谁有研究过NSMutabelData中length与bytes的关系

Question

1.length 是否为8bit为1个length
2.bytes是否和length相等
3.如果第一个问题成立那么一个lenth的意义或者代表的什么意思,为什么不用length取代bytes
4.bytes存在的意义

Answer 1

length is an NSUInteger type data, representing the length of data, and bytes is a pointer, pointing to the content of data. There is no question of equality, inequality, or whether they can be replaced with each other.

@property(readonly) NSUInteger length
The number of bytes contained by the data object.


@property(readonly) const void *bytes
A pointer to the receiver’s contents.