NSString的用法总结

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////  main.m//  String////  Created by neworigin on 14-9-17.//  Copyright (c) 2014年 Damon. All rights reserved.//#import <Foundation/Foundation.h>int main(int argc, const char * argv[]){    @autoreleasepool {        //一、NSString        /*----------------  创建字符串的方法 ----------------*/        //1、创建常量字符串。        NSString *astring1 = @"This is a String!";        NSLog(@"astring1:%@",astring1);        //2、创建空字符串，给予赋值。        NSString *astring2 = [[NSString alloc] init];        astring2 = @"This is a String!";        [astring2 release];        NSLog(@"astring2:%@",astring2);                //3、在以上方法中，提升速度:initWithString方法        NSString *astring3 = [[NSString alloc] initWithString:@"This is a String!"];        NSLog(@"astring3:%@",astring3);        [astring3 release];                //4、用标准c创建字符串:initWithCString方法        char *Cstring4 = "This is a String!";        NSString *astring4 = [[NSString alloc]initWithCString:Cstring4 encoding:NSUTF8StringEncoding];        NSLog(@"astring4:%@",astring4);        [astring4 release];                //5、创建格式化字符串:占位符（由一个%加一个字符组成）        int i = 1;  int j = 2;        NSString *astring5 = [[NSString alloc] initWithString:[NSString stringWithFormat:@"%d.This is %i string!",i,j]];        NSLog(@"astring5:%@",astring5);        [astring5 release];                //6、创建临时字符串        NSString *astring6;        astring6 = [NSString stringWithCString:"This is a temporary string" encoding:NSUTF8StringEncoding];        NSLog(@"astring6:%@",astring6);                /*----------写字符串到文件:writeToFile方法-----------*/        NSString *astring7 = [[NSString alloc] initWithString:@"This is a String!"];        NSLog(@"astring7:%@",astring7);        NSString *path1 = @"/Users/neworigin/Desktop/txt1.txt";        [astring7 writeToFile:path1 atomically:YES encoding:NSUTF8StringEncoding error:nil];        [astring7 release];                /*----从文件读取字符串:initWithContentsOfFile方法----*/                NSString *path2 = @"/Users/neworigin/Desktop/txt1.txt";        NSString *astring8 = [[NSString alloc]initWithContentsOfFile:path2 encoding:NSUTF8StringEncoding error:nil];        NSLog(@"astring8:%@",astring8);        [astring7 release];                /*----------------比较两个字符串----------------*/        //用C比较:strcmp函数        char string1[] = "string!";        char string2[] = "string!";        if(strcmp(string1, string2) == 0)        {            NSLog(@"1");        }                //isEqualToString方法        NSString *astring9 = @"This is a String!";        NSString *astring10 = @"This is a String!";        BOOL result = [astring9 isEqualToString:astring10];        NSLog(@"result:%d",result);                //compare方法(comparer返回的三种值)        NSString *astring11 = @"This is a String!";        NSString *astring12 = @"This is a String!!";        NSComparisonResult result2 = [astring11 compare:astring12];        NSLog(@"result2:%ld",result2);                //NSCaseInsensitiveSearch:不区分大小写比较   // NSLiteralSearch:进行完全比较，区分大小写    //NSNumericSearch:比较字符串的字符个数，而不是字符值。        /*-----------改变字符串的大小写------------*/        NSString *string30 = @"A String";        NSString *string31 = @"sTring";        NSLog(@"string30:%@",[string30 uppercaseString]);//大写        NSLog(@"string31:%@",[string31 lowercaseString]);//小写        NSLog(@"string31:%@",[string31 capitalizedString]);//首字母大小                /*----------------在串中搜索子串----------------*/        NSString *string13 = @"This is a string";        NSString *string14 = @"string";        NSRange range = [string13 rangeOfString:string14];        NSUInteger location = range.location;        NSUInteger leight = range.length;        NSString *astring15 = [[NSString alloc] initWithFormat:@"Location:%lu,Leight:%lu",(unsigned long)location,(unsigned long)leight];        NSLog(@"astring15:%@",astring15);        [astring15 release];                /*----------------抽取子串 ----------------*/        //-substringToIndex: 从字符串的开头一直截取到指定的位置，但不包括该位置的字符        NSString *string16 = @"This is a string";        NSString *string17 =[string16 substringToIndex:3];        NSLog(@"string17:%@",string17);        //-substringFromIndex: 以指定位置开始（包括指定位置的字符），并包括之后的全部字符        NSString *string18 = @"This is a string";        NSString *string19 = [string18 substringFromIndex:3];        NSLog(@"string19:%@",string19);        //-substringWithRange: //按照所给出的位置，长度，任意地从字符串中截取子串        NSString *string20 = @"This is a string";        NSString *string21 = [string20 substringWithRange:NSMakeRange(0, 4)];        NSLog(@"string21:%@",string21);                //扩展路径        NSString *Path3 = @"/Users/neworigin/Desktop/txt1.txt";        NSString *absolutePath = [Path3 stringByExpandingTildeInPath];        NSLog(@"absolutePath:%@",absolutePath);        NSLog(@"Path:%@",[absolutePath stringByAbbreviatingWithTildeInPath]);        //文件扩展名        NSString *Path4 = @"/Users/neworigin/Desktop/txt1.txt";        NSLog(@"Extension:%@",[Path4 pathExtension]);        return 0;    }}
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