library目录和document目录
关于这两个目录的区别我之前写过，这里还是再提一下：
document是那些暴露给用户的数据文件，用户可见，可读写；
library目录是App替用户管理的数据文件，对用户透明。所以，那些用户显式访问不到的文件要存储到这里，可读写。
获取Library目录
1.NSFileManager * defaultManager = [NSFileManager defaultManager];
2.NSURL * applicationSupportPath = [[defaultManager URLsForDirectory:NSLibraryDirectory inDomains:NSUserDomainMask]firstObject];
获取Document目录
NSFileManager * defaultManager = [NSFileManager defaultManager];
NSURL * applicationSupportPath = [[defaultManager URLsForDirectory:NSDocumentDirectory inDomains:NSUserDomainMask]firstObject];
NSFileManager * defaultManager = [NSFileManager defaultManager];
NSURL * applicationSupportPath = [[defaultManager URLsForDirectory:NSLibraryDirectory inDomains:NSUserDomainMask]firstObject];
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2
获取Document目录
读写Plist
Plist文件是iOS系统存储结构化数据的文件，方便用户进行读取（以Array和Dictionary的方式返回）。
写文件
NSArray * array = @[@”1″,@”2″,@”3″,@”4″];
NSFileManager * defaultManager = [NSFileManager defaultManager];
NSURL * documentPath = [[defaultManager URLsForDirectory:NSDocumentDirectory inDomains:NSUserDomainMask]firstObject];
NSString * fileSavePath = [documentPath.path stringByAppendingPathComponent:@”file.plist”];
BOOL success = [array writeToFile:fileSavePath atomically:YES];
写完之后，查看模拟器沙盒-写入成功，当然上述代码的返回值success也可以判断写入是否成功
读取文件
NSFileManager * defaultManager = [NSFileManager defaultManager];
NSURL * documentPath = [[defaultManager URLsForDirectory:NSDocumentDirectory inDomains:NSUserDomainMask]firstObject]
NSString * fileSavePath = [documentPath.path stringByAppendingPathComponent:@”file.plist”];
NSArray * array = [NSArray arrayWithContentsOfFile:fileSavePath];
NSLog(@”%@”,array);
注意：如果上述代码的文件不存在，则读取结果为nil。这里不需要判断是否存在。
如何创建目录？
往自己新建目录里写文件的时候，一定要判断目录是否存在，否则程序会崩溃。
使用函数来判断
– (BOOL)fileExistsAtPath:(NSString *)path isDirectory:(BOOL *)isDirectory
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如果不存在，则要创建路径
– (BOOL)createDirectoryAtPath:(NSString *)path withIntermediateDirectories:(BOOL)createIntermediates attributes:(NSDictionary *)attributes error:(NSError **)error
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createIntermediates 是创建所有不存在的父目录例如：…document/DicA/DicB/file.txt会自动创建多层目录。
attributes 通常为nil，用来设置权限，nil表示默认权限
例如
往Application Support/Demo/目录下写入,如果这个目录不存在，就创建
NSDictionary * dic = @{@”name”:@”Wenchenhuang”,@”URL”:@”blog.csdn.net/hello_hwc?viewmode=list”};
NSFileManager * defaultManager = [NSFileManager defaultManager];
NSURL * libraryPath = [[defaultManager URLsForDirectory:NSApplicationSupportDirectory inDomains:NSUserDomainMask]firstObject];
NSString * fileContainFloder = [libraryPath.path stringByAppendingPathComponent:@”DemoData”];
BOOL isDic = YES;
if (![defaultManager fileExistsAtPath:fileContainFloder isDirectory:&isDic]) {
[defaultManager createDirectoryAtPath:fileContainFloder withIntermediateDirectories:YES attributes:nil error:nil];
}
NSString * fileSavePath = [fileContainFloder stringByAppendingPathComponent:@”file.plist”];
BOOL success = [dic writeToFile:fileSavePath atomically:YES];
再看看沙盒
Application Support这个目录是Library的子目录，文档上来看，这个目录用来存放常见的对用户透明的数据，CoreData就可以存在这里。
如何保存自定义的Model
通常，自定义的Model要想使用简单的方式写入到plist文件里，要遵循NSCoding协议。然后使用NSKeyedArchiver进行编码生成NSData，读取以后使用NSUnKeyedArchiver进行解码。
定义一个Model
自定义一个Model有很多地方要实现，例如NSCopying协议，hash，isEqual函数等等，也可以使用第三方库，不过超出了本文的范畴，后续我会讲解如何写好一个Model类，这里知道NSCoding协议即可。
#import <Foundation/Foundation.h>
@interface DemoUser : NSObject<NSCoding>
@property (copy,nonatomic) NSString * name;
@property (copy,nonatomic) NSString * uniqueID;
-(instancetype)initWithName:(NSString *)name UnqiueID:(NSString *)uniqueID;
@end
#import “DemoUser.h”
@implementation DemoUser
//协议的两个必需实现的方法
-(instancetype)initWithCoder:(NSCoder *)aDecoder{
self = [super init];
if (!self) {
return nil;
}
_uniqueID = [aDecoder decodeObjectForKey:@”KUnqiueID”];
_name = [aDecoder decodeObjectForKey:@”KName”];
return self;
}
-(void)encodeWithCoder:(NSCoder *)aCoder{
-(void)encodeWithCoder:(NSCoder *)aCoder{
if (self.name != nil) {
[aCoder encodeObject:self.name forKey:@”KName”];
}
if (self.uniqueID != nil) {
[aCoder encodeObject:self.uniqueID forKey:@”KUnqiueID”];
}
}
//一个初始化方法
-(instancetype)initWithName:(NSString *)name UnqiueID:(NSString *)uniqueID{
if(self = [super init]){
_name = name;
_uniqueID = uniqueID;
}
return self;
}
@end
存入
DemoUser * user = [[DemoUser alloc] initWithName:@”wenchenhuang” UnqiueID:@”123456″];
NSMutableDictionary * dic = [[NSMutableDictionary alloc] init];
[dic setObject:@”1.0 ” forKey:@”version”];
NSData * data = [NSKeyedArchiver archivedDataWithRootObject:user];
[dic setObject:data forKey:@”user”];
//Get path
NSFileManager * defaultManager = [NSFileManager defaultManager];
NSURL * applicationSupportPath = [[defaultManager URLsForDirectory:NSApplicationSupportDirectory inDomains:NSUserDomainMask]firstObject];
NSString * fileContainFloder = [applicationSupportPath.path stringByAppendingPathComponent:@”DemoData”];
BOOL isDic = YES;
if (![defaultManager fileExistsAtPath:fileContainFloder isDirectory:&isDic]) {
[defaultManager createDirectoryAtPath:fileContainFloder withIntermediateDirectories:YES attributes:nil error:nil];
}
NSString * fileSavePath = [fileContainFloder stringByAppendingPathComponent:@”user.plist”];
BOOL success = [dic writeToFile:fileSavePath atomically:YES];
读出
NSFileManager * defaultManager = [NSFileManager defaultManager];
NSURL * applicationSupportPath = [[defaultManager URLsForDirectory:NSApplicationSupportDirectory inDomains:NSUserDomainMask]firstObject];
NSString * filePath = [applicationSupportPath.path stringByAppendingPathComponent:@”DemoData/user.plist”];
NSDictionary * dic = [NSDictionary dictionaryWithContentsOfFile:filePath];
NSString * version = [dic objectForKey:@”version”];
NSData * data = [dic objectForKey:@”user”];
DemoUser * user = [NSKeyedUnarchiver unarchiveObjectWithData:data];
NSLog(@”%@ %@”,user.name,user.uniqueID)
