Objective c 为类实例分配多个变量

我定义了一个名为StockHolding的新类，它包含类NSObject的所有方法和实例变量。并添加了3个实例变量：

@interface StockHolding : NSObject
{
    float purchaseSharePrice;
    float currentSharePrice;
    int numberOfShares;
}

@interface StockHolding : NSObject

@property float purchaseSharePrice;
@property float currentSharePrice;
@property int numberOfShares;

@end

此外，我还添加了实例方法

- (void)setPurchaseSharePrice:(float)p;
- (void)setCurrentSharePrice:(float)c;
- (void)setNumberOfShares:(int)n;

在main.m文件中，我创建了一个类的实例

StockHolding *stock = [[StockHolding alloc] init];

并希望创建和使用变量创建对象

StockHolding *a = [stock setPurchaseSharePrice:2.30 setCurrentSharePrice:4.50 setNumberOfShares:40];

但是接收错误

“StockHolding”没有可见的@interface声明选择器“setPurchaseSharePrice:setCurrentSharePrice:setNumberOfShares:”

我做错了什么？或者只是没有正确使用继承的实例

我看到了一个例子：

NSCalendar *cal = [NSCalendar currentCalendar];
NSUInteger day = [cal ordinalityOfUnit:NSDayCalendarUnit
                                inUnit:NSMonthCalendarUnit
                               forDate:now];

---

或者这不起作用？

您可以只创建一条这样的消息，而不是创建三条不同的消息-

- (void)setPurchaseSharePrice:(float)p setCurrentSharePrice:(float)c setNumberOfShares:(int)n;

那么你可以很容易地称之为。此处显示的

NSCalendar

示例与单个消息相同-

- (NSUInteger)ordinalityOfUnit:(NSCalendarUnit)smaller inUnit:(NSCalendarUnit)larger forDate:(NSDate *)date

---

与创建三条不同的消息不同，您只能创建一条这样的消息-

- (void)setPurchaseSharePrice:(float)p setCurrentSharePrice:(float)c setNumberOfShares:(int)n;

那么你可以很容易地称之为。此处显示的

NSCalendar

示例与单个消息相同-

- (NSUInteger)ordinalityOfUnit:(NSCalendarUnit)smaller inUnit:(NSCalendarUnit)larger forDate:(NSDate *)date

---

您不能像这样在一组括号中连接多个方法调用。如果要初始化

StockHolding

对象（创建新实例），则需要声明如下方法：

- (void)initWithPurchaseSharePrice:(float)p currentSharePrice:(float)c numberOfShares:(int)n;

StockHolding *a = [[StockHolding alloc] initWithPurchaseSharePrice:2.30 currentSharePrice:4.50 numberOfShares:40];

StockHolding *stock = [[StockHolding alloc] init];

StockHolding *stock = [[StockHolding alloc] init];
stock.purchaseSharePrice = whatever;

并以类似的方式实施：

- (void)initWithPurchaseSharePrice:(float)p currentSharePrice:(float)c numberOfShares:(int)n {
    self = [super init];
    if (self) {
        purchaseSharePrice = p;
        currentSharePrice = c;
        numberOfShares = n;
    }
    return self;
}

这称为初始化器方法。它创建类的新实例并返回它

然后，您可以这样使用它：

- (void)initWithPurchaseSharePrice:(float)p currentSharePrice:(float)c numberOfShares:(int)n;

StockHolding *a = [[StockHolding alloc] initWithPurchaseSharePrice:2.30 currentSharePrice:4.50 numberOfShares:40];

StockHolding *stock = [[StockHolding alloc] init];

StockHolding *stock = [[StockHolding alloc] init];
stock.purchaseSharePrice = whatever;

请注意，实际的方法名称等可以是任意的，并且不必以任何方式与实例变量的名称相关联（除非您重写

@property

s的getter和setter，但这是另一回事），因为您仍然必须自己实现该方法，并且可以在其中执行任何您想要的操作

---

如果您已经创建了这样的实例：

- (void)initWithPurchaseSharePrice:(float)p currentSharePrice:(float)c numberOfShares:(int)n;

StockHolding *a = [[StockHolding alloc] initWithPurchaseSharePrice:2.30 currentSharePrice:4.50 numberOfShares:40];

StockHolding *stock = [[StockHolding alloc] init];

StockHolding *stock = [[StockHolding alloc] init];
stock.purchaseSharePrice = whatever;

要设置变量的值，应使用

@property

s而不是实例变量：

@interface StockHolding : NSObject
{
    float purchaseSharePrice;
    float currentSharePrice;
    int numberOfShares;
}

@interface StockHolding : NSObject

@property float purchaseSharePrice;
@property float currentSharePrice;
@property int numberOfShares;

@end

之后，您可以像这样直接设置它们：

- (void)initWithPurchaseSharePrice:(float)p currentSharePrice:(float)c numberOfShares:(int)n;

StockHolding *a = [[StockHolding alloc] initWithPurchaseSharePrice:2.30 currentSharePrice:4.50 numberOfShares:40];

StockHolding *stock = [[StockHolding alloc] init];

StockHolding *stock = [[StockHolding alloc] init];
stock.purchaseSharePrice = whatever;

或

请注意，要使其工作，您不必声明或实现这些变量的setter和getter。换句话说，您可以安全地删除以下内容：

- (void)setPurchaseSharePrice:(float)p;
- (void)setCurrentSharePrice:(float)c;
- (void)setNumberOfShares:(int)n;

因为如果您使用

@property

s，编译器将自动为您添加它

---

有关实例变量和

@property

之间差异的更多信息，请阅读及其答案。您不能仅在一组括号中串联多个方法调用。如果要初始化

StockHolding

对象（创建新实例），则需要声明如下方法：

- (void)initWithPurchaseSharePrice:(float)p currentSharePrice:(float)c numberOfShares:(int)n;

StockHolding *a = [[StockHolding alloc] initWithPurchaseSharePrice:2.30 currentSharePrice:4.50 numberOfShares:40];

StockHolding *stock = [[StockHolding alloc] init];

StockHolding *stock = [[StockHolding alloc] init];
stock.purchaseSharePrice = whatever;

并以类似的方式实施：

- (void)initWithPurchaseSharePrice:(float)p currentSharePrice:(float)c numberOfShares:(int)n {
    self = [super init];
    if (self) {
        purchaseSharePrice = p;
        currentSharePrice = c;
        numberOfShares = n;
    }
    return self;
}

这称为初始化器方法。它创建类的新实例并返回它

然后，您可以这样使用它：

- (void)initWithPurchaseSharePrice:(float)p currentSharePrice:(float)c numberOfShares:(int)n;

StockHolding *a = [[StockHolding alloc] initWithPurchaseSharePrice:2.30 currentSharePrice:4.50 numberOfShares:40];

StockHolding *stock = [[StockHolding alloc] init];

StockHolding *stock = [[StockHolding alloc] init];
stock.purchaseSharePrice = whatever;

请注意，实际的方法名称等可以是任意的，并且不必以任何方式与实例变量的名称相关联（除非您重写

@property

s的getter和setter，但这是另一回事），因为您仍然必须自己实现该方法，并且可以在其中执行任何您想要的操作

---

如果您已经创建了这样的实例：

- (void)initWithPurchaseSharePrice:(float)p currentSharePrice:(float)c numberOfShares:(int)n;

StockHolding *a = [[StockHolding alloc] initWithPurchaseSharePrice:2.30 currentSharePrice:4.50 numberOfShares:40];

StockHolding *stock = [[StockHolding alloc] init];

StockHolding *stock = [[StockHolding alloc] init];
stock.purchaseSharePrice = whatever;

要设置变量的值，应使用

@property

s而不是实例变量：

@interface StockHolding : NSObject
{
    float purchaseSharePrice;
    float currentSharePrice;
    int numberOfShares;
}

@interface StockHolding : NSObject

@property float purchaseSharePrice;
@property float currentSharePrice;
@property int numberOfShares;

@end

之后，您可以像这样直接设置它们：

- (void)initWithPurchaseSharePrice:(float)p currentSharePrice:(float)c numberOfShares:(int)n;

StockHolding *a = [[StockHolding alloc] initWithPurchaseSharePrice:2.30 currentSharePrice:4.50 numberOfShares:40];

StockHolding *stock = [[StockHolding alloc] init];

StockHolding *stock = [[StockHolding alloc] init];
stock.purchaseSharePrice = whatever;

或

请注意，要使其工作，您不必声明或实现这些变量的setter和getter。换句话说，您可以安全地删除以下内容：

- (void)setPurchaseSharePrice:(float)p;
- (void)setCurrentSharePrice:(float)c;
- (void)setNumberOfShares:(int)n;

因为如果您使用

@property

s，编译器将自动为您添加它

有关StockHolding.h中实例变量和

@property

之间差异的更多信息，请阅读及其答案

@interface StockHolding : NSObject

@property (nonatomic, assign) float purchaseSharePrice;
@property (nonatomic, assign) float currentSharePrice;
@property (nonatomic, assign) int numberOfShares;

@end

@interface StockHolding : NSObject

@property (nonatomic, assign) float purchaseSharePrice;
@property (nonatomic, assign) float currentSharePrice;
@property (nonatomic, assign) int numberOfShares;

- (void)setPurchaseSharePrice:(float)iPurchase andCurrentSharePrice:(float)iCurrent withTotalNumberOfShares:(int)iTotal;

@end

持有股票

#import "StockHolding.h"

@implementation StockHolding ()

@synthesize purchaseSharePrice;
@synthesize currentSharePrice;
@synthesize numberOfShares;

@end

@implementation StockHolding ()

@synthesize purchaseSharePrice;
@synthesize currentSharePrice;
@synthesize numberOfShares;

- (void)setPurchaseSharePrice:(float)iPurchase andCurrentSharePrice:(float)iCurrent withTotalNumberOfShares:(int)iTotal {
  self.purchaseSharePrice = iPurchase;
  self.currentSharePrice = iCurrent;
  self.numberOfShares = iTotal;
}
@end

现在，每一个你想设置股票价值的类

导入库存

#导入“StockHolding.h”

创建一个对象

StockHolding*aStockHolding=[[StockHolding alloc]init]

设置值aStockHolding.numberOfShares=1或

[aStockHolding setNumberOfShares:1]

通过合成变量，默认情况下创建了getter和setter方法

---

现在，如果要在一个方法调用中设置所有值

在StockHolding.h中声明一个方法

@interface StockHolding : NSObject

@property (nonatomic, assign) float purchaseSharePrice;
@property (nonatomic, assign) float currentSharePrice;
@property (nonatomic, assign) int numberOfShares;

@end

@interface StockHolding : NSObject

@property (nonatomic, assign) float purchaseSharePrice;
@property (nonatomic, assign) float currentSharePrice;
@property (nonatomic, assign) int numberOfShares;

- (void)setPurchaseSharePrice:(float)iPurchase andCurrentSharePrice:(float)iCurrent withTotalNumberOfShares:(int)iTotal;

@end

定义StockHolding.m中的方法

#import "StockHolding.h"

@implementation StockHolding ()

@synthesize purchaseSharePrice;
@synthesize currentSharePrice;
@synthesize numberOfShares;

@end

@implementation StockHolding ()

@synthesize purchaseSharePrice;
@synthesize currentSharePrice;
@synthesize numberOfShares;

- (void)setPurchaseSharePrice:(float)iPurchase andCurrentSharePrice:(float)iCurrent withTotalNumberOfShares:(int)iTotal {
  self.purchaseSharePrice = iPurchase;
  self.currentSharePrice = iCurrent;
  self.numberOfShares = iTotal;
}
@end

在上面提到的其他类中创建对象并调用

StockHolding *aStockHolding = [[StockHolding alloc] init];
[aStockHolding setPurchaseSharePrice:22.3 andCurrentSharePrice:12.22 withTotalNumberOfShares:120]

在库存中

@interface StockHolding : NSObject

@property (nonatomic, assign) float purchaseSharePrice;
@property (nonatomic, assign) float currentSharePrice;
@property (nonatomic, assign) int numberOfShares;

@end

@interface StockHolding : NSObject

@property (nonatomic, assign) float purchaseSharePrice;
@property (nonatomic, assign) float currentSharePrice;
@property (nonatomic, assign) int numberOfShares;

- (void)setPurchaseSharePrice:(float)iPurchase andCurrentSharePrice:(float)iCurrent withTotalNumberOfShares:(int)iTotal;

@end

持有股票

#import "StockHolding.h"

@implementation StockHolding ()

@synthesize purchaseSharePrice;
@synthesize currentSharePrice;
@synthesize numberOfShares;

@end

@implementation StockHolding ()

@synthesize purchaseSharePrice;
@synthesize currentSharePrice;
@synthesize numberOfShares;

- (void)setPurchaseSharePrice:(float)iPurchase andCurrentSharePrice:(float)iCurrent withTotalNumberOfShares:(int)iTotal {
  self.purchaseSharePrice = iPurchase;
  self.currentSharePrice = iCurrent;
  self.numberOfShares = iTotal;
}
@end

现在，每一个你想设置股票价值的类

导入库存

#导入“StockHolding.h”

创建一个对象

StockHolding*aStockHolding=[[StockHolding alloc]init]

设置值aStockHolding.numberOfShares=1或

[aStockHolding setNumberOfShares:1]

通过合成变量，默认情况下创建了getter和setter方法

---

现在，如果要在一个方法调用中设置所有值

在StockHolding.h中声明一个方法

@interface StockHolding : NSObject

@property (nonatomic, assign) float purchaseSharePrice;
@property (nonatomic, assign) float currentSharePrice;
@property (nonatomic, assign) int numberOfShares;

@end

@interface StockHolding : NSObject

@property (nonatomic, assign) float purchaseSharePrice;
@property (nonatomic, assign) float currentSharePrice;
@property (nonatomic, assign) int numberOfShares;

- (void)setPurchaseSharePrice:(float)iPurchase andCurrentSharePrice:(float)iCurrent withTotalNumberOfShares:(int)iTotal;

@end

定义StockHolding.m中的方法

#import "StockHolding.h"

@implementation StockHolding ()

@synthesize purchaseSharePrice;
@synthesize currentSharePrice;
@synthesize numberOfShares;

@end

@implementation StockHolding ()

@synthesize purchaseSharePrice;
@synthesize currentSharePrice;
@synthesize numberOfShares;

- (void)setPurchaseSharePrice:(float)iPurchase andCurrentSharePrice:(float)iCurrent withTotalNumberOfShares:(int)iTotal {
  self.purchaseSharePrice = iPurchase;
  self.currentSharePrice = iCurrent;
  self.numberOfShares = iTotal;
}
@end

在上面提到的其他类中创建对象并调用

StockHolding *aStockHolding = [[StockHolding alloc] init];
[aStockHolding setPurchaseSharePrice:22.3 andCurrentSharePrice:12.22 withTotalNumberOfShares:120]

---

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