Objective-c----NSString, nsmutablestring

Directly on the code:

 
//
// main.m
//
// Created by on 15/4/2.
// Copyright (c) 2015. All rights reserved.
//

#import <Foundation / Foundation.h>
#import "Tire.h"


int main (int argc, const char * argv []) {

    // NSString class
    / *
     * Learning system classes need to grasp a few points:
     * 1. Create an object according to the given initialization method and convenience constructor method;
     * 2. Use the instance method to complete the corresponding operation according to the requirements;
     * 3. Learn to read system header files;
     * 4. Learn to learn the corresponding method through the help file.
     * /

    // Create using initialization method
// NSString * str1 = [[NSString alloc] initWithString: @ "name"];
    NSString * str1 = @ "name";
    NSLog (@ "% @", str1);
// NSString * str2 = [NSString stringWithString: @ "name"];
    NSString * str2 = @ "name";
    NSLog (@ "% @", str2);

    char * cStr = "haha";
    // Convert C language string to OC object
    NSString * str3 = [[NSString alloc] initWithCString: cStr encoding: NSUTF8StringEncoding];
    NSLog (@ "% @", str3);

    NSString * str4 = [NSString stringWithCString: cStr encoding: NSUTF8StringEncoding];
    NSLog (@ "% @", str4);

    // Create a string according to the specified format
    NSString * str5 = [[NSString alloc] initWithFormat: @ "% @ +% d", @ "en", 1001];
    NSLog (@ "% @", str5);

    NSString * str6 = [NSString stringWithFormat: @ "% @ +% d", @ "ne", 10014];
    NSLog (@ "% @", str6);

    // Create a string object based on the file contents of the specified path
    NSString * str7 = [[NSString alloc] initWithContentsOfFile: @ "/ Users / lanouhn / Desktop / test.txt" encoding: NSUTF8StringEncoding error: nil];
    NSLog (@ "% @", str7);

// NSError * err = [NSError init];
    NSString * str8 = [NSString stringWithContentsOfFile: @ "/ Users / lanouhn / Desktop / words.txt" encoding: NSUTF8StringEncoding error: nil];
    NSLog (@ "% @", str8);


    // Find the length of the string object
    NSInteger length = [str8 length];
    NSLog (@ "% ld", length);

    // Determine whether a string object has a prefix string
    BOOL result1 = [str8 hasPrefix: @ "If"];
    NSLog (@ "% @", result1? @ "YES": @ "NO");

    // Determine whether a string object has a suffix
    BOOL result2 = [str8 hasSuffix: @ "en"];
    NSLog (@ "% @", result2? @ "YES": @ "NO");

    // Determine if a string object is the same as another string object
    BOOL result3 = [str8 isEqualToString: str7];
    NSLog (@ "% @", result3? @ "YES": @ "NO");
    NSLog (@ "% d", result3);

    // String comparison and sorting results
    NSComparisonResult result4 = [str8 compare: str7];
    NSLog (@ "% ld", result4);

    // Get the substring
    // Substring starting from the specified subscript character (including modified characters) to the end of the string. The subscript starts from 0.
    NSString * subStr1 = [str8 substringFromIndex: 1];
    NSLog (@ "% @", subStr1);

    // From the beginning of the subscript 0 character to the end of the specified subscript, a string in this range
    NSString * subStr2 = [str8 substringToIndex: 2];
    NSLog (@ "% @", subStr2);

    // NSRange is a structure type, member location describes the index position, member length describes the length of the string to be intercepted
    NSRange rang = NSMakeRange (1, 3);
// rang.length = 4;
// rang.location = 2;
    NSString * subStr3 = [str8 substringWithRange: rang];
    NSLog (@ "% @", subStr3);

    // string stitching
    // Concatenate and generate a new string based on the given parameter string, without changing the original string. (Immutable string)
    NSString * newString1 = [str8 stringByAppendingString: @ "+ 100"];
    NSLog (@ "% @", newString1);

    // Generate a new string based on the given format string and parameter splicing
    NSString * newString2 = [str8 stringByAppendingFormat: @ "% d", 1001];
    NSLog (@ "% @", newString2);

    // Path stitching
    NSString * newString3 = [str8 stringByAppendingPathComponent: @ "xx.avi"];
    NSLog (@ "% @", newString3);

    // String replacement
    // Replace the strings that exist in str8 with the given second string, all are replaced
    NSString * newString4 = [str8 stringByReplacingOccurrencesOfString: @ "e" withString: @ "呵呵"];
    NSLog (@ "% @", newString4);

    // Conversion of string and numeric data
    NSString * numString1 = @ "1";
    NSInteger integerValue = [numString1 integerValue];
    NSLog (@ "% ld", integerValue);
    float integerValue1 = [numString1 floatValue];
    NSLog (@ "% f", integerValue1);

    // case conversion
    NSString * string = @ "i love you";
    // Convert to uppercase characters
    NSString * upperCaseStr = [string uppercaseString];
    NSLog (@ "% @", upperCaseStr);
    // Convert to lowercase characters
    NSString * lowercaseStr = [upperCaseStr lowercaseString];
    NSLog (@ "% @", lowercaseStr);

    // Convert to uppercase string (the first letter of each string is converted to uppercase)
    NSString * capitalString = [string capitalizedString];
    NSLog (@ "% @", capitalString);

    / *
     * Variable string
     *
     * NSMutableString
     *
     * /

    NSMutableString * mutableStr1 = [[NSMutableString alloc] init];
    NSLog (@ "% @", mutableStr1);
    NSMutableString * mutableStr2 = [NSMutableString string];

    // Concatenation of variable strings
    [mutableStr1 appendString: @ "abcdef"];
    NSLog (@ "% @", mutableStr1);
    NSString * resultString = [mutableStr1 stringByAppendingString: @ "xxxx"];

    NSLog (@ "% @", resultString);
    NSLog (@ "% @", mutableStr1);

    // Another string stitching method
    // stringByAppendingFormat: appendFormat
    [mutableStr2 appendFormat: @ "wang +% d", 1001];
    NSLog (@ "% @", mutableStr2);

    // Delete the string
    [mutableStr2 deleteCharactersInRange: NSMakeRange (2, 4)];
    NSLog (@ "% @", mutableStr2);

    // Insert string
    // Insert the specified string before the given subscript (pre-interpolation)
    [mutableStr2 insertString: @ "123" atIndex: 2];
    NSLog (@ "% @", mutableStr2);

    // Replace string
    // Replace the specified range of characters according to the given string
    [mutableStr2 replaceCharactersInRange: NSMakeRange (0, 3) withString: @ "xxx"];
    NSLog (@ "% @", mutableStr2);

     / *
     * Exercise 1:
     *
     * Given an image file name, determine whether the string starts with
     * At the end of "png", if it is, replace it with "jpg", if not, then stitch ".jpg".
     * /

    // Immutable string
    NSString * practiceStr = @ "wang / zhen / gang / .png ";
     if ([practiceStr hasSuffix: @ "png"]) {
         NSLog (@ "% @", [practiceStr stringByReplacingOccurrencesOfString: @ "png" withString: @ "jpg"]);
     }
     else {
         NSLog (@ "% @", [practiceStr stringByAppendingString: @ ". Jpg"]);
     }

     // variable string
     NSMutableString * practiceMutableStr = [[NSMutableString alloc] initWithString: @ "wang.png"];
// [practiceMutableStr appendString: @ "wang.png"]; // Note that the initialization of NSMutableSring cannot use syntactic sugar

     if ([practiceMutableStr hasSuffix: @ "png"]) {
// NSLog (@ "% @", [practiceMutableStr stringByReplacingOccurrencesOfString: @ "png" withString: @ "jpg"]);
         [practiceMutableStr replaceCharactersInRange: [practiceMutableStr rangeOfString: @ "png"] withString: @ "jpg"];
     }
     else {
         [practiceMutableStr appendString: @ ". jpg"];
     }
     NSLog (@ "% @", practiceMutableStr);



     return 0;
}

Objective-c----NSString, nsmutablestring