3

我在上课时遇到问题。我必须创建作为 NSObject 子类的“StockHolding”对象。我创建实例变量和方法。然后我创建了 3 个包含名称和价格的库存迭代，并将它们加载到一个可变数组中。我很难快速枚举数组中的对象并打印每个对象的属性（价格）。问题是我在尝试枚举对象并打印属性时遇到错误。我尝试了几种不同的方法来解决这个问题，但没有运气。有任何想法吗？我还注意到 currentStock 不是打印名称，而是打印指针位置。也许这些问题是相关的。提前致谢。

'标题'

#import <Foundation/Foundation.h>

@interface StockHolding : NSObject
{
    float fPurchaseSharePrice; 
    float fCurrentSharePrice; 
    int iNumberOfShares;
}

@property float fPurchaseSharePrice;
@property float fCurrentSharePrice;
@property int iNumberOfShares;

-(float) fCostInDollars; //fPurchaseSharePrice * fNumberOfShares
-(float) fValueInDollars; //fCurrentSharePrice * fNumberOfShares

@end

'执行'

#import "StockHolding.h"

@implementation StockHolding

@synthesize fCurrentSharePrice, fPurchaseSharePrice, iNumberOfShares;

-(float)fCostInDollars; //fPurchaseSharePrice * iNumberOfShares
{    
    return (fPurchaseSharePrice * iNumberOfShares);
}

-(float)fValueInDollars; //fCurrentSharePrice * iNumberOfShares
{
    return (fCurrentSharePrice * iNumberOfShares);
}

@end

'主要的' 

 int main(int argc, const char * argv[])
{

@autoreleasepool {
    StockHolding *Apple = [[StockHolding alloc] init];
    [Apple setFPurchaseSharePrice:225];
    [Apple setFCurrentSharePrice:300];
    [Apple setINumberOfShares:50];

    StockHolding *Cisco = [[StockHolding alloc] init];
    [Cisco setFPurchaseSharePrice:100];
    [Cisco setFCurrentSharePrice:50];
    [Cisco setINumberOfShares:75];

    StockHolding *WalMart = [[StockHolding alloc] init];
    [WalMart setFPurchaseSharePrice:75];
    [WalMart setFCurrentSharePrice:150];
    [WalMart setINumberOfShares:75];

    NSMutableArray *Portfolio = [NSArray arrayWithObjects: Apple, Cisco, WalMart, nil];

    for (NSObject *currentStock in Portfolio){   
        NSLog(@"Purchase Price: %@", currentStock );
        NSLog(@"Details: %f", [currentStock FPurchaseSharePrice]);  //  <---Error is on this line.  It says "No visible @interface for NSObject declares the selector fPurchaseSharePrice"
    }

}
return 0;
}
4

3 回答 3

2

而是为您的 for 循环执行此操作

for (StockHolding *currentStock in Portfolio){   
    NSLog(@"Purchase Price: %@", currentStock );
    NSLog(@"Details: %f", [currentStock fPurchaseSharePrice]);  //  <---Error is on this line.  It says "No visible @interface for NSObject declares the selector fPurchaseSharePrice"
}
于 2012-08-27T21:18:30.647 回答
0

在你的 NSLog:FPurchaseSharePrice中应该是fPurchaseSharePrice.

此外，如果您覆盖 -(NSString *)description，则打印该对象将产生该字符串，而不是您当前看到的该对象的指针。

- (NSString *)description
{
    return [NSString stringWithFormat:@"StockHolding: %.2f, %.2f", self.fCostInDollars, self.fValueInDollars];
}

产量：

Purchase Price: StockHolding: 11250.00, 15000.00

而不是：

Purchase Price: <StockHolding: 0x7fe438c0a480>

NSObject最后，您可以执行以下操作，而不是在 for 循环中强制转换为：

for (StockHolding *currentStock in Portfolio)

并且可能无法响应的错误将消失。

于 2012-08-27T21:17:25.330 回答
0

好吧，就像它说的那样：您没有具有该名称的方法。方法名称在 Objective-C 中区分大小写，并且您将属性（和相应的访问器）声明为fPurchaseSharePrice. 你想用这个：

NSLog(@"Details: %f", [currentStock fPurchaseSharePrice]);
于 2012-08-27T21:18:45.047 回答