如何保存NSArray並從文件中檢索NSArray

Question

我一直在試圖實現在is it possible to save NSMutableArray or NSDictionary data as file in iOS?給出的答案，他們一直沒有爲我工作。有人會告訴我我做錯了什麼嗎？我的NSArray是一個自定義對象，例如Cat。貓本身是由字符串和數字組成的。這裏是我的代碼

-(void)saveArrayToFile:(NSArray *)response; 
{ 
// NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES); 
// NSString *documentsDirectory = [paths objectAtIndex:0]; 
// NSString *filePath = [documentsDirectory stringByAppendingPathComponent:PERSISTENT_FILENAME]; 
//  
// [response writeToFile:filePath atomically:YES]; 
    NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory,NSUserDomainMask, YES); 
    if ([paths count] > 0) 
    { 
     // Path to save array data 
     NSString *arrayPath = [[paths objectAtIndex:0] stringByAppendingPathComponent:@"array.out"]; 
     // Write array 
     [response writeToFile:arrayPath atomically:YES]; 


    }else NSLog(@"NO paths"); 
} 

-(NSArray *)getArrayFromFile 
{ 
// NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES); 
// NSString *documentsDirectory = [paths objectAtIndex:0]; 
// NSString *filePath = [documentsDirectory stringByAppendingPathComponent:PERSISTENT_FILENAME]; 
// return [NSArray arrayWithContentsOfFile:filePath]; 
    NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory,NSUserDomainMask, YES); 
    if ([paths count] > 0) 
    { 
     // Path to save array data 
     NSString *arrayPath = [[paths objectAtIndex:0] stringByAppendingPathComponent:@"array.out"]; 
     NSArray *arrayFromFile = [NSArray arrayWithContentsOfFile:arrayPath]; 
     return arrayFromFile; 
    }else NSLog(@"No file to retrieve"); 
    return nil; 
} 

首先我嘗試了註釋的代碼。然後我嘗試了另一個。目前的問題是文件沒有被保存。

Answer 1

如果陣列中的內容都是屬性列表對象（的NSString，NSData的，NSArray的，或者NSDictionary的對象），此方法寫入的文件可以被用來初始化類方法arrayWithContentsOfFile一個新的數組：或實例方法initWithContentsOfFile :.

這可能是爲什麼，如果你的數組包含自定義對象

或者嘗試使用NSKeyedArchiver

Answer 2

當你保存它[響應將writeToFile您無法讀取該文件的原因：arrayPath原子：YES ]返回false。所以它不能成功保存。嘗試使用

Bool result = [NSKeyedArchiver archiveRootObject:response toFile:arrayPath]; 
NSArray *arrayFromFile = [NSKeyedUnarchiver unarchiveObjectWithFile:arrayPath]; 

在你的貓文件：

@property(nonatomic, strong)NSString* score; 
@property(nonatomic, assign)BOOL bGenuine; 
@property(nonatomic, assign)NSInteger errorCode; 

@synthesize score,bGenuine,errorCode; 

- (void)encodeWithCoder:(NSCoder *)encoder { 
    [encoder encodeObject:score forKey:@"score"]; 
    [encoder encodeObject:[NSNumber numberWithBool:bGenuine] forKey:@"bGenuine"]; 
    [encoder encodeObject:[NSNumber numberWithInt:errorCode] forKey:@"errorCode"]; 
} 

- (id)initWithCoder:(NSCoder *)decoder { 
    score = [decoder decodeObjectForKey:@"score"]; 
    bGenuine = [[decoder decodeObjectForKey:@"bGenuine"] boolValue]; 
    errorCode = [[decoder decodeObjectForKey:@"errorCode"] integerValue]; 
    return self; 
}