write to and read from files （读写文件）

1。路径
:

NSString *filePath = [NSTemporaryDirectory() stringByAppendingPathComponent:@"MyFile.txt"];

2。写入文件:

NSString : //带编码
- (BOOL)writeToFile:(NSString *)path atomically:(BOOL)useAuxiliaryFile encoding:(NSStringEncoding)enc error:(NSError
**)error
NSDictionary,NSArray,NSData,NSNumber,NSDate :
- (BOOL)writeToFile:(NSString *)path atomically:(BOOL)flag
e.g.
NSString *writeContent = @"content";
NSError *error = nil;
BOOL succeeded = [writeContent writeToFile:filePath atomically:YES encoding:NSUTF8StringEncoding error:&error];
//----------

char bytes[4] = {'a', 'b', 'c', 'd'};
NSData *dataFromBytes = [[NSData alloc] initWithBytes:bytes length:sizeof(bytes)];
BOOL succeeded = [dataFromBytes writeToFile:filePath atomically:YES]
3。读取文件:
NSString: //带编码

- (instancetype)initWithContentsOfFile:(NSString *)path encoding:(NSStringEncoding)enc error:(NSError **)error
NSDictionary,NSArray,NSData,NSNumber,NSDate :
- (id)initWithContentsOfFile:(NSString *)aPath
e.g.

NSString *readContent =[[NSString alloc] initWithContentsOfFile:filePath encoding:NSUTF8StringEncoding error:nil];
NSArray *readArray = [[NSArray alloc] initWithContentsOfFile:filePath];