每日一练：OC中Write NSString to File

#import <Foundation/Foundation.h>
int main(int argc, const char * argv[]) {    @autoreleasepool {        // insert code here...//        NSMutableString *str = [[NSMutableString stringWithUTF8String:"I have a apple"] init];        NSMutableString *str = [[NSMutableString alloc] init];        for(int i = 0; i < 10; i++) {            [str appendString:@"I have a apple, Nice One! !\n"];                        NSLog(@"the data is %@", str);            NSLog(@"the num is %d",i);        }        NSError *err;        BOOL success = [str writeToFile:@"/Users/xxxx/xxxx/test/cool.txt"                             atomically:YES                               encoding:NSUTF8StringEncoding                                  error:&err];        if(success) {            NSLog(@"Writing file is successful!");        } else {            NSLog(@"Write file is failed, with error : %@", [err localizedDescription]);        }    }    return 0;}
Result:
2018-03-13 19:19:54.668894+0800 TOCFileHandlinga[58008:3488593] the data is I have a apple, Nice One! !2018-03-13 19:19:54.669153+0800 TOCFileHandlinga[58008:3488593] the num is 02018-03-13 19:19:54.669174+0800 TOCFileHandlinga[58008:3488593] the data is I have a apple, Nice One! !I have a apple, Nice One! !2018-03-13 19:19:54.669187+0800 TOCFileHandlinga[58008:3488593] the num is 12018-03-13 19:19:54.669244+0800 TOCFileHandlinga[58008:3488593] the data is I have a apple, Nice One! !I have a apple, Nice One! !I have a apple, Nice One! !2018-03-13 19:19:54.669262+0800 TOCFileHandlinga[58008:3488593] the num is 22018-03-13 19:19:54.669277+0800 TOCFileHandlinga[58008:3488593] the data is I have a apple, Nice One! !I have a apple, Nice One! !I have a apple, Nice One! !I have a apple, Nice One! !2018-03-13 19:19:54.669291+0800 TOCFileHandlinga[58008:3488593] the num is 32018-03-13 19:19:54.669305+0800 TOCFileHandlinga[58008:3488593] the data is I have a apple, Nice One! !I have a apple, Nice One! !I have a apple, Nice One! !I have a apple, Nice One! !I have a apple, Nice One! !2018-03-13 19:19:54.669318+0800 TOCFileHandlinga[58008:3488593] the num is 42018-03-13 19:19:54.669331+0800 TOCFileHandlinga[58008:3488593] the data is I have a apple, Nice One! !I have a apple, Nice One! !I have a apple, Nice One! !I have a apple, Nice One! !I have a apple, Nice One! !I have a apple, Nice One! !2018-03-13 19:19:54.673562+0800 TOCFileHandlinga[58008:3488593] the num is 52018-03-13 19:19:54.673606+0800 TOCFileHandlinga[58008:3488593] the data is I have a apple, Nice One! !I have a apple, Nice One! !I have a apple, Nice One! !I have a apple, Nice One! !I have a apple, Nice One! !I have a apple, Nice One! !I have a apple, Nice One! !2018-03-13 19:19:54.673625+0800 TOCFileHandlinga[58008:3488593] the num is 62018-03-13 19:19:54.673636+0800 TOCFileHandlinga[58008:3488593] the data is I have a apple, Nice One! !I have a apple, Nice One! !I have a apple, Nice One! !I have a apple, Nice One! !I have a apple, Nice One! !I have a apple, Nice One! !I have a apple, Nice One! !I have a apple, Nice One! !2018-03-13 19:19:54.673652+0800 TOCFileHandlinga[58008:3488593] the num is 72018-03-13 19:19:54.674036+0800 TOCFileHandlinga[58008:3488593] the data is I have a apple, Nice One! !I have a apple, Nice One! !I have a apple, Nice One! !I have a apple, Nice One! !I have a apple, Nice One! !I have a apple, Nice One! !I have a apple, Nice One! !I have a apple, Nice One! !I have a apple, Nice One! !2018-03-13 19:19:54.674088+0800 TOCFileHandlinga[58008:3488593] the num is 82018-03-13 19:19:54.674113+0800 TOCFileHandlinga[58008:3488593] the data is I have a apple, Nice One! !I have a apple, Nice One! !I have a apple, Nice One! !I have a apple, Nice One! !I have a apple, Nice One! !I have a apple, Nice One! !I have a apple, Nice One! !I have a apple, Nice One! !I have a apple, Nice One! !I have a apple, Nice One! !2018-03-13 19:19:54.674132+0800 TOCFileHandlinga[58008:3488593] the num is 92018-03-13 19:19:54.682996+0800 TOCFileHandlinga[58008:3488593] Writing file is successful!