[iOS基础]文件读取详解

文件操作

创建文件夹：
NSString *imageDir = [NSString stringWithFormat:@"%@/Caches/%@", NSHomeDirectory(), dirName];
BOOL isDir = NO;
NSFileManager *fileManager = [NSFileManager defaultManager];
BOOL existed = [fileManager fileExistsAtPath:imageDir isDirectory:&isDir];
if ( !(isDir == YES && existed == YES) )
{
[fileManager createDirectoryAtPath:imageDir withIntermediateDirectories:YES attributes:nil error:nil];
}

删除文件夹及文件级内的文件：
NSString *imageDir = [NSString stringWithFormat:@"%@/Caches/%@", NSHomeDirectory(), dirName];
NSFileManager *fileManager = [NSFileManager defaultManager];
[fileManager removeItemAtPath:imageDir error:nil];

文件读写解析

读取txt文件

NSString *tmp;
NSArray *lines; /*将文件转化为一行一行的*/
lines = [[NSString    stringWithContentsOfFile:@"testFileReadLines.txt"]
componentsSeparatedByString:@"\n"];

NSEnumerator *nse = [lines objectEnumerator];

// 读取<>里的内容
while(tmp = [nse nextObject]) {
NSString *stringBetweenBrackets = nil;
NSScanner *scanner = [NSScanner scannerWithString:tmp];
[scanner scanUpToString:@"<" intoString:nil];
[scanner scanString:@"<" intoString:nil];
[scanner scanUpToString:@">" intoString:&stringBetweenBrackets];
NSLog([stringBetweenBrackets description]);
}

文件读取的四种方法

//第一种方法： NSFileManager实例方法读取数据
NSArray* paths = NSSearchPathForDirectoriesInDomains(NSDesktopDirectory, NSUserDomainMask, YES);
NSString* thepath = [paths lastObject];
thepath = [thepath stringByAppendingPathComponent:@"fd_list.txt"];
NSLog(@"桌面目录：%@", thepath);
NSFileManager* fm = [NSFileManager defaultManager];
NSData* data = [[NSData alloc] init];
data = [fm contentsAtPath:thepath];
NSLog(@"%@",[[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding]);

//第二种方法： NSData类方法读取数据
data = [NSData dataWithContentsOfFile:thepath];
NSLog(@"NSData类方法读取的内容是：%@",[[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding]);

//第三种方法： NSString类方法读取内容
NSString* content = [NSString stringWithContentsOfFile:thepath encoding:NSUTF8StringEncoding error:nil];
NSLog(@"NSString类方法读取的内容是：\n%@",content);

//第四种方法： NSFileHandle实例方法读取内容
NSFileHandle* fh = [NSFileHandle fileHandleForReadingAtPath:thepath];
data = [fh readDataToEndOfFile];
NSLog(@"NSFileHandle实例读取的内容是：\n%@", [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding]);