Common uses of NSString in iOS

Common usage of IOS nsstring//1, creating constant strings. NSString *astring = @ "This is a string!"; 2, create an empty string, give the assignment. NSString *astring = [[NSString alloc] init]; Astring = @ "This is a string!";  /3, in the above method, the lifting speed: Initwithstring method NSString *astring = [[NSString alloc] initwithstring:@ "This is a string!"]; 4. Create a string with standard C: Initwithcstring method Char *cstring = "This is a string!";  NSString *astring = [[NSString alloc] initwithcstring:cstring]; 5. Create a formatted string: placeholder (consisting of a% plus one character) int i = 1; int j = 2; NSString *astring = [[NSString alloc] initwithstring:[nsstring stringwithformat:@ "%d.this is%i string!", I,j]]; NSLog (@ "astring:%@", astring); 6, create temporary string nsstring *astring;  astring = [NSString stringwithcstring: "This is a temporary string"]; 7. Create string from file NSString *path = [[Nsbundlemainbundle] pathforresource:@ "astring" oftype:@ "txt"]; NSString *astring = [[NSString alloc] initwithcontentsoffile:path]; 8. Create string with string and write to file nsstring *astring = [[NSString alloc] initwithstring:@ "This is a string!"]; NSLog (@ "astring:%@", astring); NSString *path = @ "Astring.text"; [astring Writetofile:path Atomically:yes]; Note: This path is only indicative, the true path is not so//9, compared with C: strcmp function char string1[] = "string!"; Char string2[] = "string!"; if (strcmp (string1, string2) = = 0) {NSLog (@ "1");}//10, isequaltostring method NSString *astring01 = @ "This is a string!" ; NSString *astring02 = @ "This is a string!"; BOOL result = [Astring01 isequaltostring:astring02]; NSLog (@ "result:%d", result),//11, compare method (three values returned by comparer)//nsstring *astring01 = @ "This is a string!";     NSString *astring02 = @ "This is a string!";    BOOL result = [Astring01 compare:astring02] = = Nsorderedsame;     Nsorderedsame judge whether the content is the same NSLog (@ "result:%d", result);    BOOL result = [Astring01 compare:astring02] = = nsorderedascending; Nsorderedascending determines the size of two object values (in alphabetical order, ASTRING02 is greater than ASTRING01) NSLog (@ "result:%d", result);    BOOL result = [Astring01 compare:astring02] = = nsordereddescending;      Nsordereddescending determines the size of two object values (in alphabetical order, ASTRING02 is less than ASTRING01) NSLog (@ "result:%d", result); 12, do not consider the case comparison string//1.nsstring *astring01 = @ "This is a string!"; NSString *astring02 = @ "This is a string!";    BOOL result = [Astring01 caseinsensitivecompare:astring02] = = Nsorderedsame; Nsordereddescending determines the size of two object values (in alphabetical order, ASTRING02 is less than ASTRING01) NSLog (@ "result:%d", result); 2.NSString *astring01 = @ "This is a string!"; NSString *astring02 = @ "This is a string!"; BOOL result = [Astring01 compare:astring02 options:nscaseinsensitivesearch |    Nsnumericsearch] = = Nsorderedsame; Nscaseinsensitivesearch: Case-insensitive comparison nsliteralsearch: Make a full comparison, case-sensitive nsnumericsearch: Compares the number of characters in a string, not the character value.  NSLog (@ "result:%d", result);  13. Output uppercase or lowercase string nsstring *string1 = @ "A string";  NSString *string2 = @ "String"; NSLog (@ "string1:%@", [string1 uppercasestring]);//Uppercase NSLog (@ "string2:%@", [string2 lowercasestring]);//lowercase NSLog (@ " string2:%@ ", [string2 capitalizedstring]);//first letter size//14,-rangeofstring://Find string somewhere contains other strings nsstring *string1 = @" This is A string "; NSString *string2 = @ "string"; Nsrange range = [string1 rangeofstrING:STRING2]; int location = Range.location; int leight = Range.length; NSString *astring = [[NSString alloc] initwithstring:[nsstring stringwithformat:@ "location:%i,leight:%i", location, Leight]]; NSLog (@ "astring:%@", astring); [Astring release]; 15,-substringtoindex: From the beginning of the string is truncated to the specified position, but does not include the position of the character nsstring *string1 = @ "This is a string"; NSString *string2 = [string1 substringtoindex:3]; NSLog (@ "string2:%@", string2); 16,-substringfromindex: Start at the specified position (including the character at the specified position), and include all subsequent characters nsstring *string1 = @ "This is a string"; NSString *string2 = [string1 substringfromindex:3]; NSLog (@ "string2:%@", string2); 17,-substringwithrange://In accordance with the given position, length, arbitrarily intercept the substring from the string nsstring *string1 = @ "This is a string"; NSString *string2 = [string1 substringwithrange:nsmakerange (0, 4)]; NSLog (@ "string2:%@", string2); 18,-stringwithcapacity://According to fixed length to generate an empty string nsmutablestring *string; String = [nsmutablestring stringwithcapacity:40]; 19.-appendstring:and-appendformat://Connect one string to the end of another string nsmutablestring *string1 = [[NsmutablestRing Alloc] initwithstring:@ "This is a nsmutablestring"]; [String1 appendstring:@], I'll be adding some character "]; [String1 appendformat:[nsstring stringwithformat:@ ", I'll be adding some character"]]; NSLog (@ "string1:%@", String1);//20,-insertstring:atindex://Insert string at specified location nsmutablestring *string1 = [[nsmutablestring Alloc] initwithstring:@ "This is a nsmutablestring"]; [String1 insertstring:@] hi! [atindex:0]; NSLog (@ "string1:%@", String1); 21,-setstring:nsmutablestring *string1 = [[Nsmutablestring alloc] initwithstring:@ "This is a nsmutablestring"]; [String1 setstring:@ "Hello word!"]; NSLog (@ "string1:%@", String1); 22,-replacecharactersinrange:withstring://Replace the string with the specified string in the specified position, length of the string nsmutablestring *string1 = [[nsmutablestring Alloc] initwithstring:@ "This is a nsmutablestring"]; [String1 replacecharactersinrange:nsmakerange (0, 4) withstring:@ "that"]; NSLog (@ "string1:%@", String1); 23,-hasprefix://Check whether the string begins with another string nsstring *string1 = @ "NSStringInformation.txt"; [String1 Hasprefix:@ "NSString"] = = 1? NSLog (@ "YES"): NSLog (@ "NO");  [String1 hassuffix:@ ". txt"] = = 1? NSLog (@ "YES"): NSLog (@ "NO"); 24, extension path nsstring *path = @ "~/nsdata.txt"; NSString *absolutepath = [Path Stringbyexpandingtildeinpath]; NSLog (@ "absolutepath:%@", Absolutepath); NSLog (@ "path:%@", [Absolutepath Stringbyabbreviatingwithtildeinpath]);//25, file extension nsstring *path = @ "~/nsdata.txt"; NSLog (@ "extension:%@", [Path pathextension]);