JDTuple: Implementing a Tuple Data Structure in Objective‑C for Simplified Parameter Handling

The article begins by highlighting the cumbersome nature of arrays and dictionaries in Objective‑C and proposes a tuple solution that can encapsulate any data without worrying about type or bounds, making OC code feel more like Swift.

It explains the concept of a tuple—originally a relational‑database row—and shows how a tuple can be represented as tuple1 = ("阿强", 18, "战士") , containing ordered or keyed elements that are immutable after definition.

Basic usage of JDTuple is demonstrated with the jd_tuple(...) constructor, e.g.: NSString *name = @"阿珍"; NSInteger age = 28; NSArray *arr = @[@"a", @"b", @"c"]; JDTuple *someTuple = jd_tuple(name, age, arr); The library supports anonymous tuples, sequential unpacking via jd_unpack(tuple)^(...){...} , and key‑based unpacking with jd_unpackWithkey(...) , allowing developers to extract only needed elements or ignore others using the arg_ph placeholder.

Implementation details cover how JDTuple stores values using an NSMutableArray of NSValue objects and a NSMutableDictionary mapping keys to indices. It leverages variadic functions and va_start / va_arg to read arguments, using a custom end marker ( jd_tuple_end ) instead of nil . Type encodings are obtained automatically with @encode(typeof(var)) , eliminating manual type specification.

Macros simplify tuple creation: #define jd_tuple(...) ({JDTuple *t = [JDTuple new]; [t tupleInputKeys:#__VA_ARGS__]; t.addArg(___tuple_add(__VA_ARGS__)); t;}) . Additional macros generate key lists, count arguments, and support strict unpacking ( jd_unpack_strict ) that enforces exact type matches at compile time.

Data retrieval can be performed by index or key using subscript syntax, e.g. NSValue *value = someTuple[0]; or NSValue *value = someTuple[@"age"]; . Batch key‑based unpacking is achieved through overloaded functions and helper macros that map keys to variables.

The article also showcases practical applications such as returning multiple values from a method, creating a universal performSelector_tuple: that accepts a tuple of arguments and returns a tuple of results, and converting JSON strings into tuples for lightweight data parsing.

Finally, it notes some pitfalls (e.g., BOOL vs. _Bool, architecture‑dependent sizes of CGFloat and NSInteger) and provides references to type‑encoding documentation, ReactCocoa, and macro techniques, with the source code hosted on Gitee.