问题描述
我有大约 50 个描述类似路径"的 CGPoint 对象，我想将它们添加到 NSArray.这将是一个只返回给定索引对应的 CGPoint 的方法.我不想创建 50 个变量，例如 p1 = ...;p2 = ...，依此类推.有没有一种简单的方法可以让我在使用对象初始化 NSArray 时立即"定义这些点?
I have about 50 CGPoint objects that describe something like a "path", and I want to add them to an NSArray. It's going to be a method that will just return the corresponding CGPoint for an given index. I don't want to create 50 variables like p1 = ...; p2 = ..., and so on. Is there an easy way that would let me to define those points "instantly" when initializing the NSArray with objects?
推荐答案
通过 UIKit Apple 为 NSValue 添加了对 CGPoint 的支持，所以你可以这样做:
With UIKit Apple added support for CGPoint to NSValue, so you can do:
NSArray *points = [NSArray arrayWithObjects:
[NSValue valueWithCGPoint:CGPointMake(5.5, 6.6)],
[NSValue valueWithCGPoint:CGPointMake(7.7, 8.8)],
nil];
列出与 CGPoint 一样多的 [NSValue] 实例，并以 nil 结束列表.此结构中的所有对象都是自动释放的.
List as many [NSValue] instances as you have CGPoint, and end the list in nil. All objects in this structure are auto-released.
另一方面，当您从数组中提取值时:
On the flip side, when you're pulling the values out of the array:
NSValue *val = [points objectAtIndex:0];
CGPoint p = [val CGPointValue];
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