objective-c - 使用 NSObjects 将文件保存到文档 NSMutableArray 的问题

我是一名新手 iOS 开发人员。 我编写了一个小应用程序，它保存了一个 NSMutableArray 数组，其中包含从 NSObject 派生的对象。 应用程序进行保存，但文件未在文档目录中创建，应用程序无法读取。 这个问题在模拟器和我的 iPhone 3gs 4.2.1 上都有

我在 appDelegate 类中的 NSMutableArray 定义:

@property (nonatomic,retain, readwrite) NSMutableArray *places;

我的 NSObject 类:

 #import <Foundation/Foundation.h>


@interface Place : NSObject {
    NSString *name;
    NSString *location;
}

-(id) initNSString *)name: (NSString *)location;

@property (retain,nonatomic,readwrite) NSString *name;
@property (retain,nonatomic,readwrite) NSString *location;

@end

我的 StorageService 库类:

 #import "StorageService.h"


@implementation StorageService

-(id) init {
    self = [super init];
    if (self != nil) {

    }
    return self;
}


-(void) saveArrayToFileNSString*) filename : (NSMutableArray *)arrayToSave{
    // get full path
    NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
    NSString *fullPath = [paths objectAtIndex:0];
    fullPath = [fullPath stringByAppendingPathComponent:filename];  
    NSLog(@"Save in %@",fullPath);
    [arrayToSave writeToFile:fullPath atomically:YES];
}

-(NSMutableArray*) readArrayFromFileNSString *)filename {
    // get full path
    NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
    NSString *fullPath = [paths objectAtIndex:0];
    fullPath = [fullPath stringByAppendingPathComponent:filename];

    if ([[NSFileManager defaultManager] fileExistsAtPath:fullPath]) {
        NSMutableArray *data = [[NSMutableArray alloc] initWithContentsOfFile:fullPath];
        if (data == nil) {
            data = [[NSMutableArray alloc] init];
        }
        NSLog(@"Read from %@",fullPath);
        return data;
    } else {
        NSMutableArray *data = [[NSMutableArray alloc] initWithContentsOfFile:fullPath];
        return data;
    }
}

-(void) dealloc {
    [super dealloc];
}

@end

和appDelegate中的My函数:

    -(void) saveApplicationData {
    [self.storageService saveArrayToFile : PLACES_FILE : self.places];
}

-(void) loadApplicationData {
    self.places = [self.storageService readArrayFromFileLACES_FILE];
}

这是我的类，它对文件名保持不变:

    #import <Foundation/Foundation.h>

extern NSString * const PLACES_FILE = @"laces.dat";

@interface ApplicationConstants : NSObject {

}

@end

那么有什么问题呢？

谢谢你们。

---

Best Answer-推荐答案

您想要的是让 Place 符合 NSCoding 协议(protocol)，以允许对文件进行序列化(如果需要，还可以在内存中数据)

将 Place 扩展为 (我还更改了 init 方法的名称，因为您的名字违反了 iOS 的所有命名惯例):

@interface Place : NSObject <NSCoding> {
    NSString *name; 
    NSString *location; 
}

-(id)initWithNameNSString *)name locationNSString *)location;

@property (retain,nonatomic,readwrite) NSString *name; 
@property (retain,nonatomic,readwrite) NSString *location;

@end

您的实现非常简单，但您还需要实现 NSCoding 协议(protocol)定义的两个方法:

@implementation Place

@synthesize name, location;

-(id)initWithNameNSString *)aName locationNSString *)aLocation {
    self = [super init];
    if (self) {
        self.name = aName;
        self.location = aLocation;
    }
    return self;
}

-(id)initWithWithCoderNSCoder)decoder {
    self = [super initWithCoder:decoder];
    if (self) {
       self.name = [decoder decodeObjectForKey"name"];
       self.location = [decoder decodeObjectForKey"location";
    }
    return self;
}

-(void)encodeWithCoderNSCoder*)encoder {
    [encoder encodeObject:self.name forKey"name"];
    [encoder encodeObject:self.location forKey"location"];
    [super encodeWithCoder:encoder];
}

@end

有了这个，将 places 数组保存到磁盘就像这样简单:

[NSKeyedArchiver archiveRootObject:places toFile:path];

解码同样简单:

places = [[KSKeyUnarchiver unarchiveObjectWithFile:path] retain];

关于objective-c - 使用 NSObjects 将文件保存到文档 NSMutableArray 的问题，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/7038428/