cocoa-touch - 将对象转换为字典以保存为 plist : property list invalid format

Question

我想将对象数组作为 plist 文件保存到磁盘。

首先，我将对象数组转换为等效字典数组。对于某些属性来说没有问题，但有些属性会出现错误。现在我正在尝试获取 url 属性错误。 (注释行也有问题，但我现在不处理。

这是YOEvento类的接口(interface)。

#import <MapKit/MapKit.h>

@interface YOEvento : NSObject

{
    NSURL *url; // <url>
    NSInteger identificador; // <identificador>
    NSString *nombre; // stores the <name> tag
    NSDate *diaDeInicio; // stores the tag <dia-de-inicio>
    NSDate *diaDeFin; // stores the tag <dia-de-fin>
    NSString *entradilla; // stores the tag <entradilla>
    NSURL *foto; // <foto>
    CLLocationCoordinate2D localizacion; // <localizacion>
    BOOL isFavourite;
}

@property (nonatomic, retain) NSURL *url;
@property NSInteger identificador;
@property (nonatomic, retain) NSString *nombre;
@property (nonatomic, retain) NSDate *diaDeInicio;
@property (nonatomic, retain) NSDate *diaDeFin;
@property (nonatomic, retain) NSString *entradilla;
@property (nonatomic, retain) NSURL *foto;
@property CLLocationCoordinate2D localizacion;
@property BOOL isFavourite;

@end

转换数组的代码

        // 1. Convert array of YoEvento in array of Dictionary to be able to save as plist

    NSMutableArray *tempArray = [NSMutableArray array];
    for (YOEvento *evento in self.eventosFavouritesAppDel) {
        NSDictionary *dict = [NSDictionary dictionaryWithObjects:[NSArray arrayWithObjects:
                                                                  evento.url,
//                                                                  evento.identificador,
                                                                  evento.nombre,
                                                                  evento.diaDeInicio,
                                                                  evento.diaDeFin,
                                                                  evento.entradilla,
//                                                                  evento.foto,
//                                                                  evento.localizacion,
                                                                  nil]
                                                         forKeys:[NSArray arrayWithObjects:
                                                                  kURLElement,
//                                                                  kIdentificadorElement,
                                                                  kNombreElement,
                                                                  kDiaDeInicioElement,
                                                                  kDiaDeFinElement,
                                                                  kEntradillaElement,
//                                                                  kFotoElement,
//                                                                  kLocalizacionElement,
                                                                  nil]];
        [tempArray addObject:dict];
    }
        // 2. Convert the array to NSData
    NSString *errorDesc;
    NSData *data = [NSPropertyListSerialization dataFromPropertyList:tempArray format:NSPropertyListXMLFormat_v1_0 errorDescription:&errorDesc];

在执行最后一条指令后，我收到错误描述“属性列表格式无效”错误。字典里的内容看来是有效的。以下是运行时内容的日志:

Printing description of dict:
<CFBasicHash 0x5b99170 [0x1298400]>{type = immutable dict, count = 5,
entries =>
    0 : <CFString 0xfd00 [0x1298400]>{contents = "entradilla"} = <CFString 0x5b99b10 [0x1298400]>{contents = "Festival Internacional de Cine de Gij\u00f3n  M\u00e1s informaci\u00f3n en  www.gijonfilmfestival.com "}
    2 : <CFString 0xfcd0 [0x1298400]>{contents = "nombre"} = <CFString 0x5b99590 [0x1298400]>{contents = "49 FICXix\u00f3n - Festival Internacional de Cine de Gij\u00f3n"}
    4 : <CFString 0xfcb0 [0x1298400]>{contents = "url"} = <CFURL 0x5b992f0 [0x1298400]>{type = 15, string = http://www.gijon.es/eventos/show/18753-49-ficxixon-festival-internacional-de-cine-de-gijon, encoding = 134217984, base = (null)}
    5 : <CFString 0xfcf0 [0x1298400]>{contents = "dia-de-fin"} = 2011-11-26 22:59:00 +0000
    6 : <CFString 0xfce0 [0x1298400]>{contents = "dia-de-inicio"} = 2011-11-18 22:59:00 +0000
}

Answer 1

属性列表只能包含少量类的对象:即 NSString、NSDate、NSNumber、NSArray、NSDictionary、NSData。如果您想在属性列表中表示其他类型(例如 NSURL)，则必须首先将其转换为允许的类型之一。