iOS读写json文件的方法示例

//两种获取应用沙盒路径的不同方法
NSString *documentPath = [NSHomeDirectory() stringByAppendingPathComponent:@"Documents"];
NSString *cachePath = [NSHomeDirectory() stringByAppendingPathComponent:@"Library/Caches"];
NSString *preferencesPath = [NSHomeDirectory() stringByAppendingPathComponent:@"Library/Preferences"];
NSString *tmpPath = [NSHomeDirectory() stringByAppendingPathComponent:@"tmp"];

//NSSearchPathForDirectoriesInDomains()返回的是一个数组，这是因为对于Mac OS可能会有多个目录匹配某组指定的查询条件，但是在iOS上只有一个匹配的目录
NSString *documentPath1 = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES).lastObject;
NSString *cachePath1 = NSSearchPathForDirectoriesInDomains(NSCachesDirectory, NSUserDomainMask, YES).lastObject;
NSString *tmpPath1 = NSTemporaryDirectory();

//传入一个json数据，返回一个foundation对象
+ (id)JSONObjectWithData:(NSData *)data options:(NSJSONReadinGoptions)opt error:(NSError * _Nullable *)error;

//传入foundation对象，转化为json数据
+ (NSData *)dataWithJSONObject:(id)obj options:(NSJSONWritingOptions)opt error:(NSError * _Nullable *)error;

NSArray *array = @[@1, @2, @3];
 NSDictionary *dic = [NSDictionary dictionaryWithObjectsAndKeys:array,@"1",@"dongdong", @"name", nil];
 
 //首先判断能否转化为一个json数据，如果能，接下来先把foundation对象转化为NSData类型，然后写入文件
 if ([NSJSONSerialization isValidJSONObject:dic]) {
 NSData *jsonData = [NSJSONSerialization dataWithJSONObject:dic options:1 error:nil];
 [jsonData writeToFile:jsonPath atomically:YES];
 }
 
 //在读取的时候首先去文件中读取为NSData类对象，然后通过NSJSONSerialization类将其转化为foundation对象
 NSData *jsonData = [[NSFileManager defaultManager] contentsAtPath:jsonPath];
 NSArray *jsonDic = [NSJSONSerialization JSONObjectWithData:jsonData options:1 error:nil];