Objc-C Knowledge Point Review 4 NSString and NSMutableString

Objc-C Knowledge Point Review 4 NSString and NSMutableString

1. NSString // NSString: unchangeable string. Once created, you cannot modify // initialization method // create an empty string NSString * string1 = [[NSString alloc] init]; NSLog (@ "% @", string1); // create an NSString object NSString * string2 = [[NSString alloc] initWithString: @ "iPhone"] based on the given constant string; NSLog (@ "% @", string2); // constant area string NSString * string3 = @ "iPhone"; NSLog (@ "% @", string3 ); NSLog (@ "% p", string3); // output address // if other variables exist in the string to be created, you need to create NSInteger version = 6 using initWithFormat; NSS Tring * string4 = [[NSString alloc] initWithFormat: @ "iPhone % ld", version]; NSLog (@ "% @", string4 ); // convenience constrtor NSString * str1 = [NSString string]; NSLog (@ "% @", str1); NSString * str2 = [NSString stringWithString: @ "iOS"]; NSLog (@ "% @", str2); NSString * str3 = @ "iOS"; NSLog (@ "% @", str3); NSString * str4 = [NSString stringWithFormat: @ "iOS % ld", version]; NSLog (@ "% @", str4); // obtain the string length // NSUInteger length = [Str4 length]; // call the getter method // NSLog (@ "% lu", length); NSLog (@ "% lu", str4.length ); // point syntax // determine whether the string starts or ends with a pin string * str5 = @ "abcdpp123"; // constant area string NSString * str6 = [[NSString alloc] initWithFormat: @ "abcdpp123"]; // heap string // prefix BOOL result = [str6 hasPrefix: @ "abd"]; NSLog (@ "% d", result ); // suffix result = [str6 hasSuffix: @ "23"]; NSLog (@ "% d", result); // string truncation (substring truncation) // obtain the abc (prefix string) NSString * subStr1 = [str6 s UbstringToIndex: 3]; NSLog (@ "% @", subStr1); // obtain 123 (end string) NSString * subStr2 = [str6 substringFromIndex: 6]; NSLog (@ "% @", subStr2); // obtain dpp (intermediate string) // nsange range = {3, 3}; NSString * subStr3 = [str6 substringWithRange: NSMakeRange (3, 3)]; NSLog (@ "% @", subStr3); // concatenated string NSString * newSubStr = [subStr1 stringByAppendingString: subStr2]; NSLog (@ "% @", subStr1); NSLog (@ "% @", subStr2); NSLog (@ "% @", newSubStr ); NSLog (@ "% p", newSubStr); // output address NSString * newSubStr1 = [NSString stringWithFormat: @ "% @", subStr1, subStr2]; NSLog (@ "% @", newSubStr1); NSLog (@ "% p", newSubStr1 ); // output address // replace string // @ "NBA"-> @ "CBA"; NSString * str7 = @ "NBANNN"; NSString * newSubStr2 = [str7 stringByReplacingOccurrencesOfString: @ "N" withString: @ "C"]; NSLog (@ "% @", newSubStr2) // string comparison // @ "NBA" and @ "CBA "; // NSString * str8 = @ "NBA"; // NSSt Ring * str9 = @ "CBA"; NSString * str8 = [[NSString alloc] initWithFormat: @ "NBA123456aa"]; NSString * str9 = [[NSString alloc] initWithFormat: @ "NBA123456aa"]; // isw.tostring compares the string content if ([str8 isw.tostring: str9]) {NSLog (@ "string equal ");} else {NSLog (@ "inconsistent");} // = compare whether the two objects are consistent. if the objects are consistent, their content must be consistent if (str8 = str9) {NSLog (@ "Equal string");} else {NSLog (@ "inconsistent ");} // convert the string and value types to each other // @ "123" // convert the string and value type to a number. If the value is not a number, the conversion is stopped. For NSString * str10 = @ "123a456"; int a = [str10 intValue]; NSLog (@ "% d", a); NSInteger B = [str10 integerValue]; NSLog (@ "% ld", B); // case-sensitive conversion operation // @ "ios"-> @ "iOS" NSString * str11 = @ "ios "; // all upper case NSString * newStr = [str11 uppercaseString]; NSLog (@ "% @", newStr); // upper case NSLog (@ "% @", [str11 capitalizedString]); // all lowercase nslogs (@ "% @", [str11 lowercaseString]); 2. NSMutableString: Variable string // @ "iPhone" // create variable string, container The size is an expected value. Generally, it is written as 0, so that the system allocates space NSMutableString * mString = [[NSMutableString alloc] initWithCapacity: 0]; NSLog (@ "% @", mString); // Add the string [mString appendString: @ "iPhone"]; NSLog (@ "% @", mString); [mString appendFormat: @ "iPhone % ld ", version]; NSLog (@ "% @", mString); // Insert the string [mString insertString: @ "" atIndex: 6]; NSLog (@ "% @", mString); // Delete the string [mString deleteCharactersInRange: NSMakeRange (0, 7)]; NSLo G (@ "% @", mString); // specify ". NSMutableString * name = [[NSMutableString alloc] initWithCapacity: 0]; [name appendString: @ "blue ocean .png"]; if ([name hasPrefix: @ "png"]) {NSLog (@ "ending with 'png '"); [name replaceCharactersInRange: NSMakeRange (name. length-3, 3) withString: @ "jpg"];} else {NSLog (@ "not ending with 'png"); [name appendString :@". jpg "];} NSLog (@" % @ ", name );