Question

我正在尝试访问目标C类中的结构。但我是不成功。任何人都可以解释如何调整这个类使其编译和访问成员变量？

#import <Foundation/Foundation.h>

enum ACCOUNT_TYPE {    
        SAVINGS,   
        LOAN,   
        FIXED_DEPOSIT  
};

struct SavingsData {  
        NSMutableString* accountName;  
        NSMutableString* accountType;  
        NSMutableString* balance;  
        NSMutableString* currency;  
};  

struct LoanData {  
        NSMutableString* accountName;  
        NSMutableString* balance;  
};  

struct FixedDepositData {  
        NSMutableString* accountName;  
        NSMutableString* depositAmount;  
        NSMutableString* roi;  
};

union AccountData {  
        struct SavingsData *savingsData;  
        struct LoanData *loanData;  
        struct FixedDepositData *fixedDepositData;  
};

@interface Account : NSObject {  
        NSMutableString* accountId;  
        enum ACCOUNT_TYPE type;  
        union AccountData *accountData;  
}

@property (nonatomic, assign) NSMutableString* accountId;  
@property (nonatomic, assign) enum ACCOUNT_TYPE type;  
@property (nonatomic, assign) union AccountData *accountData;

Answer 1

尝试以下方法（显示一个例子但适用于所有人），使用typedef并将名称移到声明之外....

typedef enum {    
        SAVINGS,   
        LOAN,   
        FIXED_DEPOSIT  
} ACCOUNT_TYPE;

你使用......

ACCOUNT_TYPE type;  
AccountData accountData;

Answer 2

你应该让它静止

@interface Account : NSObject {  
        union AccountData accountData;  
}

@property (nonatomic, assign) union AccountData accountData;

否则，您需要在init中动态创建它（或将其设置为NULL）。此外，您需要确保结构中的所有这些NSMutableString指针都已正确初始化为nil或其他。此外，您应该小心内存管理，因为在传递字符串时不会保留字符串（您可以覆盖结构的setter / getter以相应地保留/释放NSMutableString）。

Answer 3

我建议使用typedef关键字：

typedef NS_ENUM(NSUInteger, ACCOUNT_TYPE) {
    SAVINGS = 0,
    LOAN,
    FIXED_DEPOSIT
};

typedef struct _SavingsData {  
        NSMutableString* accountName;  
        NSMutableString* accountType;  
        NSMutableString* balance;  
        NSMutableString* currency;  
} SavingsData; 

@interface Account : NSObject

@property (nonatomic, strong) NSMutableString* accountId;  
@property (nonatomic, assign) ACCOUNT_TYPE type;  
@property (nonatomic, assign) SavingsData savingData; 

@end

现在您可以将此类用作：

Account *acc = [Account new];
acc.type = SAVINGS;
SavingsData savData = {..., ...};
acc.savingsData = savData;

Answer 4

我建议使用子类化：

@interface Account : NSObject {
    NSMutableString *accountId;
    NSMutableString *accountName;
}
@end

@interface SavingsAccount : Account {
    NSMutableString *accountType;
    NSMutableString *balance;
    NSMutableString *currency;
}
@end

@interface LoanAccount : Account {
    NSMutableString *balance;
}
@end

@interface FixedDepositAccount : Account {
    NSMutableString *depositAmount;
    NSMutableString *roi;
}
@end

属性被剪切，并且accountName被移动到基类Account，因为它在所有3个子类中都很常见。

如何在objectiveC类中使用struct和union？

4 个答案: