無法將我的類的NSMutableArray保存到文件（IOS）

Question

找不到爲什麼我的代碼無法工作。請幫助別人。

我創建了我自己的類，實現了NSCoding協議。不知道我想念或錯誤。

這裏是節省代碼

NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory , NSUserDomainMask, YES); 
NSString *documentsDirectory = [paths objectAtIndex:0]; 
NSString *fileName = [documentsDirectory stringByAppendingPathComponent:@"Currency.plist"]; 

Item * item = [[Item alloc] init]; 
item.x = 3; item.y = 5; item.type = (TType) 3; item.isSelected = NO; 

NSMutableArray * array = [[NSMutableArray alloc] init]; 
[array addObject:item]; 

[array fileName atomically:YES] // (Doesn't Save the file ,returns NO); 

這裏是我的類的代碼 * .H *

#import <Foundation/Foundation.h> 

enum TType 
{ 
    kNone = 0, 
    KFirst = 1, 
    .... 
}; 

@interface Item : NSObject <NSCoding>{ 

} 

@property (nonatomic) int x; 
@property (nonatomic) int y; 
@property (nonatomic) enum TType type; 
@property (nonatomic) BOOL isSelected; 

@end 

.M

@implementation Item 
@synthesize x, y , type , isSelected; 

#pragma mark NSCoding Protocol 

- (void)encodeWithCoder:(NSCoder *)encoder; 
{ 
    [encoder encodeInt32:[self x] forKey:@"x"]; 
    [encoder encodeInt32:[self y] forKey:@"y"]; 
    [encoder encodeInt32:[self type] forKey:@"type"]; 
    [encoder encodeBool:[self isSelected] forKey:@"isSelected"]; 
} 

- (id)initWithCoder:(NSCoder *)decoder; 
{ 
    if (![super init]) 
     return nil; 

    [self setX:[decoder decodeInt32ForKey:@"x"]]; 
    [self setY:[decoder decodeInt32ForKey:@"y"]]; 
    [self setType:(TType)[decoder decodeInt32ForKey:@"color"]]; 
    [self setIsSelected:[decoder decodeBoolForKey:@"isSelected"]]; 

    return self; 
} 

@end 

Answer 1

我想你會發現你在答案：objects conforming to nscoding will not writetofile

即你不能序列您Item類屬性列表，因爲它不是一個屬性列表對象（NSString，NSData，NSArray，或者NSDictionary）。

查看文檔writeToFile:atomically:：

這種方法遞歸地驗證了所有包含的對象是寫出來的文件之前，屬性列表對象，並返回NO如果所有的對象都沒有屬性列表對象，因爲生成的文件不會是有效的屬性列表。