关于NSJSONReadingOptions参数的含义

enum{

NSJSONReadingMutableContainers=(1UL<<0),

NSJSONReadingMutableLeaves=(1UL<<1),

NSJSONReadingAllowFragments=(1UL<<2)

};typedefNSUIntegerNSJSONReadingOptions;

数组中含以上三种参数，

第一种：

NSJSONReadingMutableContainers

Specifies that arrays and dictionaries are created as mutable objects.

是说被创建的数组或者字典应该是可变的

第二种：

NSJSONReadingMutableLeaves

Specifies that leaf strings in the JSON object graph are created as instances of NSMutableString.

是说JSON对象中的被创建的字符串是NSMutableString类型的

第三种：

NSJSONReadingAllowFragments

Specifies that the parser should allow top-level objects that are not an instance of NSArray or NSDictionary.

这一句是说解析出的顶层对象可以允许不是NSArray或NSDictionary类型的