objective-c - NSMutableArray:添加和提取结构

Question

我正在尝试将一些数据存储在 NSMutableArray 中.这是我的结构:

typedef struct{
    int time;
    char name[15];
}person;

这是添加一个人的代码:

person h1;
h1.time = 108000;
strcpy(h1.name, "Anonymous");
[highscore insertObject:[NSValue value:&h1 withObjCType:@encode(person)] atIndex:0];

所以，我尝试以这种方式提取:

NSValue * value = [highscore objectAtIndex:0];
person p;
[value getValue:&p];
NSLog(@"%d", p.time);

问题是最后的日志没有显示 108000!
怎么了？

Answer 1

正如我在最初的评论中所说，很少有理由用纯 c 结构来做这种事情。而是使用真正的类对象:

如果您不熟悉下面的语法，您可能需要查看这些 ObjC 2.0 上的快速教程以及阅读 Apple 的文档:

A Quick Objective-C 2.0 Tutorial

A Quick Objective-C 2.0 Tutorial: Part II

人物等级:

// "Person.h":
@interface Person : NSObject {}

@property (readwrite, strong, nonatomic) NSString *name;
@property (readwrite, assign, nonatomic) NSUInteger time; 

@end

// "Person.m":
@implementation Person

@synthesize name = _name; // creates -(NSString *)name and -(void)setName:(NSString *)name
@synthesize time = _time; // creates -(NSUInteger)time and -(void)setTime:(NSUInteger)time

@end

类用途:

#import "Person.h"

//Store in highscore:

Person *person = [[Person alloc] init];
person.time = 108000; // equivalent to: [person setTime:108000];
person.name = @"Anonymous"; // equivalent to: [person setName:@"Anonymous"];
[highscore insertObject:person atIndex:0];

//Retreive from highscore:

Person *person = [highscore objectAtIndex:0]; // or in modern ObjC: highscore[0];
NSLog(@"%@: %lu", person.name, person.time);
// Result: "Anonymous: 108000"

为了简化调试，您可能还需要 Person 来实现 description 方法:

- (NSString *)description {
    return [NSString stringWithFormat:@"<%@ %p name:\"%@\" time:%lu>", [self class], self, self.name, self.time];
}

这将允许您仅执行此操作以进行日志记录:

NSLog(@"%@", person);
// Result: "<Person 0x123456789 name:"Anonymous" time:108000>