问题
What is the difference between initializing array with
NSArray * array = [NSArray array];
and
NSArray * array = @[];
回答1:
NSArray * array = @[]; is the new way of doing NSArray * array = [NSArray array];
回答2:
@[] is shorthand for:
id a = nil;
NSArray* array = [NSArray arrayWithObjects:&a count:0];
Which is really just shorthand for [NSArray array], for all intents and purposes.
This is a feature added in a particular version of the compiler (and doesn't actually require runtime support for this particular syntax).
It is not at all like the @"" shorthand in that @"" produces a compile time constant and will cause no messaging at runtime. In fact, @"" (any @"sequence") is a special case in that it emits a compile time constant that is realized in the runtime with zero messaging; zero dynamism. A @"..." is more similar to an Objective-C class than it is to a regular instance of an object.
来源：https://stackoverflow.com/questions/14483531/nsarray-initialization-methods