iOS 文件读写

#import <Foundation/Foundation.h>

@interface Utils : NSObject
+(void) writeFile:(NSString *) filePath data:(NSString *) _data;
+(NSString *) readFile:(NSString *) filePath;
@end

#import "Utils.h"

@implementation Utils
+(void) writeFile:(NSString *) filePath data:(NSString *) _data{
    NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
    NSString* fileName = [[paths objectAtIndex:0]stringByAppendingPathComponent:filePath];
    NSLog(@"File %@ will write!", fileName);

    // 用这个方法来判断当前的文件是否存在，如果不存在，就创建一个文件
    NSFileManager *fileManager = [NSFileManager defaultManager];
    if ( ![fileManager fileExistsAtPath:fileName]) {
        NSLog(@"File %@ not exists!", fileName);
        [fileManager createFileAtPath:fileName contents:nil attributes:nil];
    }else NSLog(@"File %@ exists!", fileName);

    [_data writeToFile:fileName atomically:YES encoding:NSUTF8StringEncoding error:NULL];
}

+(NSString *) readFile:(NSString *) filePath{
    NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
    NSString* fileName = [[paths objectAtIndex:0]stringByAppendingPathComponent:filePath];
    NSLog(@"File %@ will write!", fileName);

    NSString* myString = [NSString stringWithContentsOfFile:fileName usedEncoding:NULL error:NULL];
    return myString;
}
@end

调用：

[Utils writeFile:@"/Lein.txt" data:@"123QWE金属材料"];
    NSLog(@"Lein.txt:%@", [Utils readFile:@"/Lein.txt"]);