如何返回两个值?

问题描述

我想返回一个笛卡尔坐标 (x, y)，作为两个 int s.我看到的唯一方法是创建一个类并返回它的一个实例.

I'd like to return a Cartesian coordinate (x, y), as two ints. The only way I see is to create a class and return an instance of it.

如何从Objective C中的方法返回两个值?

How to return two values from a method in Objective C?

推荐答案

你只能从一个函数中返回一个值(就像 C 语言一样)，但该值可以是任何东西，包括一个结构体.并且由于您可以按值返回结构，因此您可以定义这样的函数(借用您的示例):

You can only return one value from a function (just like C), but the value can be anything, including a struct. And since you can return a struct by value, you can define a function like this (to borrow your example):

-(NSPoint)scalePoint:(NSPoint)pt by:(float)scale
{
    return NSMakePoint(pt.x*scale, pt.y*scale);
}

这仅适用于小型/简单结构.

This is only really appropriate for small/simple structs.

如果你想返回多个新的对象，你的函数应该使用指向对象指针的指针，因此:

If you want to return more than one new object, your function should take pointers to the object pointer, thus:

-(void)mungeFirst:(NSString**)stringOne andSecond:(NSString**)stringTwo
{
    *stringOne = [NSString stringWithString:@"foo"];
    *stringTwo = [NSString stringWithString:@"baz"];
}

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