Objective c 如何使用arrayWithContentsOfFile加载在Objective/XCode中使用writeToFile成功写入的文件

我正在将自定义对象数组保存到plist列表文件中，如下所示：

+(void) arrayToPlist: (NSArray*) plant_types{
    NSMutableArray* dictionary_array = [NSMutableArray arrayWithCapacity: plant_types.count];

    for(int i = 0; i<plant_types.count; i++){
        PlantType* pt = [plant_types objectAtIndex: i];
        [dictionary_array addObject: [pt toDict]];
    }

    NSString *rootPath = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) objectAtIndex:0];
    NSString* filePath    = [rootPath stringByAppendingPathComponent:@"PlantTypes.plist"];
    NSLog(@"Writing plist to: %@", filePath);

    [dictionary_array writeToFile: filePath atomically: YES];  
}

+（void）数组plist:（NSArray*）植物类型{
NSMutableArray*dictionary_array=[NSMutableArray阵列容量：plant_types.count]；
对于具有plist的（inti=0；i，此代码返回正确的结果

+(NSMutableArray*) arrayFromPlist{
    NSLog(@"Loading array of plant types from plist.");

    NSString *rootPath = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) objectAtIndex:0];
    NSString* filePath    = [rootPath stringByAppendingPathComponent:@"PlantTypes.plist"];
    NSFileManager*  fileManager = [NSFileManager defaultManager];

    if([fileManager fileExistsAtPath:filePath]){ 
        NSLog(@"Plist file exists at expected location.");
        NSMutableArray* plant_dicts = [NSMutableArray arrayWithContentsOfFile:filePath];
        NSLog(@"Loaded array with contents of file, got %d plant types.", plant_dicts.count);
        NSMutableArray* plant_types = [NSMutableArray arrayWithCapacity: plant_dicts.count];
        for(int i = 0; i< plant_dicts.count; i++){
            NSMutableDictionary* dict = [plant_dicts objectAtIndex: i];
            [plant_types addObject: dict];
        }
        return plant_types;
    }
    NSLog(@"Plant Type plist file not found.");
    return NULL;
}

我认为问题来自PlantType的实现。您可以发布代码（toDict和fromDict方法）
这一行：

NSMutableDictionary* dict = [plant_dicts objectAtIndex: i];

不返回可变字典，但返回不可变字典

如果您希望它是可变的，您应该按照以下思路做一些事情：

MutableDictionary* dict = [NSMutableDictionary dictionaryWithDictionary: [plant_dicts objectAtIndex: i]];

是的，对于要执行isEqualToString的字符串，原因与Java中相同。==只检查指针是否相同，而不是字符串的内容。该==在渲染代码中起作用，因为编译器知道它可以对同一字符串的两个实例使用同一指针。但是如果其中一个字符串来自plist，它将是一个不同的指针。
2012-02-22 16:24:43.697 Test[5574:10103] Loading array of plant types from plist.
2012-02-22 16:24:43.698 Test[5574:10103] Plist file exists at expected location.
2012-02-22 16:24:43.699 Test[5574:10103] Loaded array with contents of file, got 5 plant types.
2012-02-22 16:24:43.700 Test[5574:10103](
        {
        name = "Autumn Olive";
        radius = 10;
    },
        {
        name = "Dwarf Cherry";
        radius = 5;
    },
        {
        name = Bamboo;
        radius = 2;
    },
        {
        name = Pomegranate;
        radius = 6;
    },
        {
        name = Lupin;
        radius = "0.6000000238418579";
    }
)

NSMutableDictionary* dict = [plant_dicts objectAtIndex: i];

MutableDictionary* dict = [NSMutableDictionary dictionaryWithDictionary: [plant_dicts objectAtIndex: i]];