Question

Aaron Hillegass（第17部分的练习）。

问题：在我的循环中，我希望它记录3个StockHolding对象中每个对象的值，但是现在它只记录DHL的值。如何让循环记录其他2个对象的值？

谢谢！

P.S。 StockHolding.h和StockHolding.m没事。

import <Foundation/Foundation.h>
import "StockHolding.h"
int main(int argc, const char * argv[]) {

@autoreleasepool {

    StockHolding *DHL = [[StockHolding alloc] init];
    [DHL setPurchaseSharePrice:345.67];
    [DHL setNumberOfShares:23];
    [DHL setCurrentSharePrice:389.23];

    StockHolding *Sony = [[StockHolding alloc] init];
    [Sony setPurchaseSharePrice:587.12];
    [Sony setNumberOfShares:14];
    [Sony setCurrentSharePrice:603.81];

    StockHolding *EPAM = [[StockHolding alloc] init];
    [EPAM setPurchaseSharePrice:178.45];
    [EPAM setNumberOfShares:35];
    [EPAM setCurrentSharePrice:190.64];

    NSMutableArray *result = [[NSMutableArray alloc] initWithObjects:DHL, Sony, EPAM, nil];

    for (NSObject *n in result) {
    NSLog(@"Purchase for: %f\nNumber of shares: %d\nCurrent share price: %f\nCost,$: %f\nValue,$: %f\n", DHL.purchaseSharePrice, DHL.numberOfShares, DHL.currentSharePrice, DHL.costInDollars, DHL.valueInDollars);
    }
}
return 0;
}

问题解决了：

#import <Foundation/Foundation.h>
#import "StockHolding.h"

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

@autoreleasepool {


    StockHolding *DHL = [[StockHolding alloc] init];
    [DHL setNameOfShare:@"DHL"];
    [DHL setPurchaseSharePrice:345.67];
    [DHL setNumberOfShares:23];
    [DHL setCurrentSharePrice:389.23];

    StockHolding *Sony = [[StockHolding alloc] init];
    [Sony setNameOfShare:@"Sony"];
    [Sony setPurchaseSharePrice:587.12];
    [Sony setNumberOfShares:14];
    [Sony setCurrentSharePrice:603.81];

    StockHolding *EPAM = [[StockHolding alloc] init];
    [EPAM setNameOfShare:@"EPAM"];
    [EPAM setPurchaseSharePrice:178.45];
    [EPAM setNumberOfShares:35];
    [EPAM setCurrentSharePrice:190.64];

    NSMutableArray *result = [[NSMutableArray alloc] initWithObjects:DHL, Sony, EPAM, nil];

    for (StockHolding *n in result) {
    NSLog(@"\nName: %@\nPurchase for: %.2f\nNumber of shares: %lu\nCurrent share price: %.2f\nCost,$: %.2f\nValue,$: %.2f\n", n.nameOfShare, n.purchaseSharePrice, n.numberOfShares, n.currentSharePrice, n.costInDollars, n.valueInDollars);
    }
}
return 0;
}

还有另一种选择：

[result enumerateObjectsUsingBlock:^(StockHolding *DHL, NSUInteger idx, BOOL *stop) {
        NSLog(@"\nName: %@\nPurchase for: %.2fl\nNumber of shares: %lu\nCurrent share price: %.2fl\nCost,$: %.2fl\nValue,$: %.2fl\n", DHL.nameOfShare, DHL.purchaseSharePrice, (unsigned long)DHL.numberOfShares, DHL.currentSharePrice, DHL.costInDollars, DHL.valueInDollars);
}];

谢谢大家！

Answer 1

我不确定你要做什么，但看起来代码末尾的for循环是错误的。我想你正试图为三个StockHolding变量中的每一个运行NSLog？你写它的方式，它只是重复DHL的值3次。

请改为尝试：

for (StockHolding *n in result) {
    NSLog(@"Purchase for: %f\nNumber of shares: %d\nCurrent share price: %f\nCost,$: %f\nValue,$: %f\n", 
           n.purchaseSharePrice, 
           n.numberOfShares, 
           n.currentSharePrice, 
           n.costInDollars, 
           n.valueInDollars);
}

如何访问NSMutableArray中对象的属性？

1 个答案: