NSMutableDictionary不检索对象

Question

EmployeesArray = [[NSMutableArray alloc] initWithCapacity:100];
    Employees *Emp1 = [[Employees alloc] init];    
    Emp1.Number = 1;
    Emp1.Name = @"Jamal";
    Emp1.Age = 16;
    Emp1.Gender = @"Male";
  [EmployeesArray addObject:Emp1];
 [Dic1 setValue:Emp1 forKey:@"A"];

- (IBAction)Retrieve:(id)sender {

  Employees *objEmp2 = [Dic1 valueForKey:@"A"];
    printf(objEmp2.Name);

}

为什么这段代码不能检索名字？和错误出现??

Answer 1

有三件事可能会有所帮助。

1. 使用-setObject:forKey:代替-setValue:forKey 因为您使用自定义类，所以请使用objectForKey而不是valueForKey。
2. 通常，使用objective-c样式-NSLog()代替c样式代码会更容易。
3. 确保已导入包含Employees类定义的头文件，而不是仅将其用作当前.m文件的转发类。

Answer 2

您需要使用setObject:forKey和objectForKey:方法，而不是setValue:forKey:和valueForKey:

Answer 3

您是否初始化了Dic1字典？

// try doing this
Dic1 = [[NSMutableDictionary alloc] init];

EmployeesArray = [[NSMutableArray alloc] initWithCapacity:100];
    Employees *Emp1 = [[Employees alloc] init];    
    Emp1.Number = 1;
    Emp1.Name = @"Jamal";
    Emp1.Age = 16;
    Emp1.Gender = @"Male";
  [EmployeesArray addObject:Emp1];
 [Dic1 setObject:Emp1 forKey:@"A"];

- (IBAction)Retrieve:(id)sender {

  Employees *objEmp2 = [Dic1 objectForKey:@"A"];
    printf(objEmp2.Name);

}