iOS中NSString

1 NSString不可变字符串

char *s = @"hello.world";

NSString *str = @"Hello";//字符串格式

//OC，Ｃ　字符串的转换

NSString *str1 = [NSString stringWithUTF8String:s];//C ->OC

NSLog(@"str2=@s" ,[str UTF8String]);//OC->C

//创建字符串

NSString *str3 = @"iOS";

NSString *str4 = [[NSString alloc]init];

//格式化字符串

int a =10;

int b= 20;

NSString *str5 = [NSString stringWithFormat:@"a=%d,b=%d,"a,b];

//字符串拼接

NSString *str6 = [str5 stringByAppendingString:str3];

NSLog(@"str6=%@".str6);

//大小写转换

//A->a

NSString *str7 = @"ABCDE";

NSString str8 = [str7 lowercaseString];

//a->A

NSString *str9 = @"abdee";

NSString *str10 = [str9 uppercaseString];

//前缀和后缀的判断

NSString *str11 = @"www.imooc.com";

BOOL hasPerfix = [str11  hasPrefix:@"www."];

if(hasPrefix){

NSLog(@"有对应的前缀");

else{
NSLog(@"没有对应的前缀");

BOOL hasSuffix = @".com";

if (hasSuffix){

NSLog(@"有对应的后缀");

else{

NSLog（@"没有对应的后缀"）；

//分割字符串

NSString *str12 @"a,b,c,d,e";

NSArray *strArray = [str12 componentsSeparatedByStrin:@","];

for( NSString *str in strArray){

NSLog(@"str = %@"，str);//str =a, str = a....

//按照范围截取字符串

NSRange  range =NSMakeRange(1,5);

NSString *str13 = [str12 substringWithRange:range];

//从某一位截取后面的字符串

NSString *str14 = [str12 substringFormIndex:2];//从第二位开始截取后面的

NSString *str15 = [str12  substringToindex:4];//从开头截取的第四位

//将字符串拆分为每一个字符

for (int i=0; i<[str12 length];i++)

{ NSLog(@"%c",[str12 characterAtIndex:i]);

//查找

NSString *str15 = @"ab, ce ,ef, gh";

//查找指定字符串的位置

NSRange range1 =[str15 rangeofStrin:@"ab"];

NSlog(@"range1.location:%ld,range1.lengt;h",range1.location,range1.length);

//字符串的替换

NSString *str 16 = @"hello,ios,word";

NSString *str17 = [str16 stringByReplacingCharctersInRange:NSMakeRange(0,5) withString:@"你好"]；

NSLog(@"str17=%@",str17);

//用指定字符串替换原字符串中的字符

// stringByReplacingOccurencesofString-源字符串中要被替换的内容

NSString *str20 = [str16 stringByReplacingOccurrencesofString:@"hello"withString:@"你好"];

//读取文件

//文件来源 1 ：本地文件，2 网络文件

//路径

NSString *strg = @www.baidu.com;

//网络路径

NSURL　＊httpURL = [NSURL URLWithString:strg];

//本地路径

NSURL＊fileURL＝[NSURL fileURLWithPath: strg];

//读取网络文件

NSString *httpStr = [NSString stringWithContentsofURL:httpURL encoding:USUTF8StringEncoding error:nil];

//读取本地文件

NSString *fileStr = [NSString stringWithContentsoffile: @"/USers/Visitor/Desktop/test.txt" encoding:NSUTF8StringEncoding error:nil];

//写入文件

NSString *strg1 = @"Hello,Visitor";

[strg1 writeTofile:@"USers/Visitor/Desk/demo.txt" atomically:YES encoding:NSUTF8StringEncoding: error :nil];

//可变字符串 (是字符串的子类)

NSMutableString *str = [[NSMutableString alloc]initWithCapacity:10];

[str1 setString:@"hello"];

//追加字符串

[str appendSting:@" word"];

[str appendFormat:@"-%@".a];

//替换字符串

NSRange range = [str rangeofString:@"word"];

[str replaceCharactersInRange:range withString:@"ios"];

//插入字符串

[str insertString:@"A" atIndex:6];

//删除字符串

NSRange range1 = [str rangeofString:ios];

[str deleteCharactersINRange:range];