iOS development OC (17)--foundation (2) NSString and simple string read and write

NSString: Immutable string

Nsmutablestring: variable string

Note:The URL cannot read the file named Chinese, otherwise null, cannot be read, to change to English

// URL read file is omnipotent

Here are some of the features of the Code

1. Create and read

voidstringcreate () {/*1. How to create a string*/NSString*S1 =@"Jack"; //nsstring *s2 = [[NSString alloc] initwithstring:@ "Jack"];NSString*S3 = [[NSString alloc] Initwithformat:@"Age is %d",Ten]; //C String ---OC stringNSString *S4 = [[NSString alloc] initwithutf8string:"Jack"]; //OC String ---C string    Const Char*cs =[S4 Utf8string]; //Read File//nsutf8stringencoding used in Chinese can use this codeNSString *S5 = [[NSString alloc] Initwithcontentsoffile:@"/users/apple/desktop/1.txt"encoding:nsutf8stringencoding Error:nil]; //URL: Resource Path//protocol Header://Path//File://    //ftp://    // Http://weibo.com/a.png    // http://www.baidu.com        //This is the read local file//Nsurl *url = [[Nsurl alloc] initwithstring:@ "file:///users/apple/desktop/1.txt "];Nsurl*url = [Nsurl Fileurlwithpath:@"/users/apple/desktop/1.txt"]; NSString*S6 =[[NSString alloc] Initwithcontentsofurl:url encoding:nsutf8stringencoding Error:nil]; NSLog (@"s6=\n%@", S6); /*provides a class method to quickly return an object to someone else, without the need for alloc ... Initwith .... Very slow generally there is a class method paired with an object method (class method usually begins----urlwithstring.     ) [Nsurl urlwithstring:<# (NSString *) #>];     [NSString stringwithformat:@ ""]; [NSString stringwithcontentsoffile:<# (NSString *) #> encoding:<# (nsstringencoding) #> error:<# (          Nserror *__autoreleasing *) #>]; */}    

2. Write

voidStringexport () {//Write String (try not to create. rtf, will not open)[@"Jack\njack"WriteToFile:@"/users/apple/desktop/my.txt"atomically:yes encoding:nsutf8stringencoding Error:nil]; NSString*str =@"4234234"; Nsurl*url = [Nsurl Fileurlwithpath:@"/users/apple/desktop/my2.txt"]; [Str writetourl:url atomically:yes encoding:nsutf8stringencoding Error:nil];//atomically Atomic Nature//every line in the file is \ n}

3. Simple Application

intMain () {nsmutablestring*S1 = [Nsmutablestring stringWithFormat:@"My age is ten"]; //stitching the contents to the back of the S1[S1 appendString:@" One"]; //get the scope of isNsrange range = [S1 rangeofstring:@" is"];        [S1 Deletecharactersinrange:range]; NSString*S2 = [NSString stringWithFormat:@"Age is ten"]; NSString*S3 = [S2 stringbyappendingstring:@" One"]; NSLog (@"s1=%@, s2=%@", S1, S2); return 0;}

There are a lot of uses, please refer to the official documents, that is the true path of iOS, the origin.

iOS development OC (17)--foundation (2) NSString and simple string read and write