objective-c - 数组中的所有对象(从 csv 解释)作为同一个对象(最后一个对象)返回

Question

我想要实现的是将 csv 文件转换为自定义对象数组，但是，我对此的尝试似乎导致数组中的所有对象都作为同一对象返回(数组中的最后一个对象)。

在我进一步解释之前，这里是代码:

- (NSArray *)arrayFromCSVFileName:(NSString *)csvFileName fileType:(NSString *)fileType {

// Convert the file into an NSData object
NSString *studentFilePath = [[NSBundle mainBundle] pathForResource:csvFileName ofType:fileType];
NSData *studentData = [NSData dataWithContentsOfFile:studentFilePath];

// Convert the NSData into an NSString
NSString *csvString = [[NSString alloc] initWithData:studentData encoding:NSUTF8StringEncoding];

// Split each record (line) in the csvDataString into an individual array element (split on the newline character \n)
NSArray *csvArray = [csvString componentsSeparatedByString:@"\n"];

// Create an array to hold the parsed CSV data
NSMutableArray *parsedCSVArray = [[NSMutableArray alloc] init];

NSMutableArray *elementArray = [[NSMutableArray alloc] init];

CGSElement *elementToAdd = [[CGSElement alloc] init];

// Loop through each line of the file
for (int i = 0; i < [csvArray count]; i++) {

    // Get a reference to this record (line) as a string, and remove any extranous new lines or alike
    NSString *csvRecordString = [[csvArray objectAtIndex:i] stringByReplacingOccurrencesOfString:@"\r" withString:@""];

    // Split the line by the comma delimeter
    NSArray *csvRecordArray = [csvRecordString componentsSeparatedByString:@","];

    // Check that there are actually fields (i.e. this is not a blank line)
    if ( ([csvRecordArray count] > 0) && ([[csvRecordArray objectAtIndex:0] length] > 0) ) {

        elementToAdd.mass = [[csvRecordArray objectAtIndex:1] floatValue];
        elementToAdd.atomicNumber = [[csvRecordArray objectAtIndex:0] intValue];
        elementToAdd.name = [csvRecordArray objectAtIndex:2];
        elementToAdd.symbol = [csvRecordArray objectAtIndex:3];
        elementToAdd.period = [[csvRecordArray objectAtIndex:4] intValue];

        [elementArray addObject:elementToAdd];

    }

}

for (int i = 0; i < [elementArray count]; i++) {

    NSLog(@"%i", i);

    CGSElement *current = [elementArray objectAtIndex:i];

    NSLog(@"Name = %@", current.name);

}

// Return the parsed array
return elementArray;
}

有问题的自定义对象是 CGSElement 对象，我试图填充 elementArray和。但是，我的调试代码(以下代码段):

for (int i = 0; i < [elementArray count]; i++) {

    NSLog(@"%i", i);

    CGSElement *current = [elementArray objectAtIndex:i];

    NSLog(@"Name = %@", current.name);

}

结果，不是返回所有正确的元素名称，而是返回最后一个元素(将其放在上下文中，ununoctium)118 次。

经过一些测试，我可以放心地说，直到这一点之后:

elementToAdd.mass = [[csvRecordArray objectAtIndex:1] floatValue];
elementToAdd.atomicNumber = [[csvRecordArray objectAtIndex:0] intValue];
elementToAdd.name = [csvRecordArray objectAtIndex:2];
elementToAdd.symbol = [csvRecordArray objectAtIndex:3];
elementToAdd.period = [[csvRecordArray objectAtIndex:4] intValue];

所有元素都被正确定义，而不是一遍又一遍地定义相同的元素。

不用说，我很困惑为什么它会一遍又一遍地返回同一个对象。任何帮助，将不胜感激。

Answer 1

这一行:

CGSElement *elementToAdd = [[CGSElement alloc] init];

应该在您的循环内，就在您尝试编辑对象并将其添加到数组之前。目前，您正在反复修改同一个对象，而不是为每条记录创建新对象。