从数组返回对象属性的总值

Question

我正在尝试从数组totalPurchaseSum中的所有对象获取属性stockPurchasePrice的总值arrPurchaseActions。

这是属性（user.h）：

@property (nonatomic, strong) NSMutableArray *arrPurchaseActions;

@property (nonatomic) CGFloat totalSumPurchased;

-(CGFloat)totalSumPurchased:(CGFloat)stockPurchasePrice;

这是我尝试使用的方法（User.m）：

-(CGFloat)totalSumPurchased:(CGFloat)stockPurchasePrice
{
    CGFloat totalSumPurchased = 0;
    size_t count = [self.arrPurchaseActions count];
    for (int i = 0; i < count; i++) {
            totalSumPurchased = totalSumPurchased +        [[self.arrPurchaseActions[i].stockPurchasePrice];
}

    return totalSumPurchased;
}

有人可以帮我解决这个问题吗？

Answer 1

试试这个：

NSNumber * sum = [self.arrPurchaseActions valueForKeyPath:@"@sum.stockPurchasePrice"];

Answer 2

这一行：

totalSumPurchased = totalSumPurchased + [[self.arrPurchaseActions[i].stockPurchasePrice];

需要：

totalSumPurchased = totalSumPurchased + [[self.arrPurchaseActions[i] stockPurchasePrice];

您不能将属性访问器与id类型的对象一起使用（NSArray objectAtIndex:返回的对象）。相反，请为属性调用getter方法。