In the FoundObjective-c Foundation of Objective-c, common classes 2 -- NSString and NSMut

Continue NSString, because many are used, we should focus on understanding 1. Evaluate the string length [cpp] NSString * myName = @ "AOBAMA"; int length = (int) [myName length]; // It is found that the return value type is NSUInteger. If the conversion is not strong or warning, you do not know whether strong conversion is a common method. I hope you can tell NSLog (@ "the string length is: % d ", length); if ([myName length]> 5) {NSLog (@" AAAAA "); // print AAAAA} 2. string-related conversions change case sensitivity [cpp] NSString * string = @ "Where are You, Boy! "; // All capital NSLog (@" % @ ", [string uppercaseString]); // print where are you, BOY! // All lowercase NSLog (@ "% @", [string lowercaseString]); // print where are you, boy! // All words Are capitalized, and other letters Are lowercase NSLog (@ "% @", [string capitalizedString]); // print Where Are You, Boy! Convert a string to the basic data type [cpp] NSString * aboutFloat = @ "3.14"; NSString * aboutBool = @ "NO"; NSLog (@ "% f ", [aboutFloat floatValue]); // print 3.140000 NSLog (@ "% d", [aboutBool boolValue]); // print 0 // convert the float type to an integer NSLog (@ "% d", [aboutFloat intValue]); // print 3 merge two strings into one [cpp] // method 1 NSString * str1 = @ "Hello"; NSString * str2 = @ "World "; NSString * str3 = [[NSString alloc] initWithFormat: @ "% @", str1, str2]; NSLog (@ "str1 and str2 are merged into st R3 result: % @ ", str3); // print the result: the result of merging str1 and str2 into str3 is: hello World // method 2 NSString * str4 = [str1 stringByAppendingString: str2]; NSLog (@ "the result of merging str1 and str2 into str4 is: % @", str4 ); // print the result: str1 and str2 are merged into str4 and the result is: Hello World // connect multiple strings NSString * str5 = [str1 stringByAppendingFormat: @ "% @", str1, str2, str3]; NSLog (@ "str5 is: % @", str5); // print the result: str5 is: helloHello WorldHello World 3. Whether to start with a string hasPrefix: whether to end with a string hasSuffix [cpp] NSStri Ng * str6 = @ "who are you"; BOOL isStart1 = [str6 hasPrefix: @ "wh"]; BOOL isStart2 = [str6 hasPrefix: @ "h"]; BOOL isEnd1 = [str6 hasSuffix: @ "u"]; BOOL isEnd2 = [str6 hasSuffix: @ "o"]; NSLog (@ "Result: % d ,,, % d, % d, % d ", isStart1, isStart2, isEnd1, isEnd2); // result: 1, 0, 1 ,,, 0 4. truncate the string into an array [cpp] NSString * str7 = @ "you/have/a/baby"; NSArray * array = [str7 componentsSeparatedByString: @ "/"]; NSLog (@ "% @", array); // number The Group can print the result directly without traversing/* printing (you, have, a, baby) */5, string truncation [cpp] NSString * str8 = [str7 substringFromIndex: 2]; // blocks starting from the second location include 2, of course NSLog starting with 0 (@ "% @", str8 ); // u/have/a/baby NSString * str9 = [str7 substringToIndex: 5]; // from the start to the specified position, but does not include this location NSLog (@ "% @", str9); // you/h // intercept the nsange range = NSMakeRange (2, 3) According to the range ); // define the range first. You can also define the nsange range = {2, 3}; NSLog (@ "location .. % ld length... % ld ", range. location, range. length );/ /Location .. 2 length... 3 range. location = 3; // includes 2 range. length = 4; // NSLog (@ "location .. % ld length... % ld ", range. location, range. length); // location .. 3 length... 4 NSString * str10 = [str7 substringWithRange: range]; NSLog (@ "% @", str10); // hav 6. String Query [cpp] www.2cto. comNSRange range2 = [str7 rangeOfString: @ "have"]; nsange range3 = [str7 rangeOfString: @ "aaa"]; NSLog (@ "location1... % ld ", range 2. location); NSLog (@ "location2... % ld ", range3.location); printed result: location1... 4 location2... 9223372036854775807 the search result can be determined based on the position of the source string to be queried. Usage of NSMutableString