NSString基本用法

            字符串创建

<span style="font-size:14px;">//常量字符串，存储在常量区(@"dsds"相同，则str,str6是同一个,地址相同)        NSString *str = @"dsds";        NSString *str6 = @"dsds";                //使用类方法创建字符串        NSString * string = [NSString string];        string = @"小白";//字符串赋值               //创建一个字符串，并且将内容设置为string        NSString * string1 = [NSString  stringWithString:string];                //格式化创建字符串(按照格式输出)        NSString * string2 = [NSString stringWithFormat:@"%@",string1];        NSString * string0 = [NSString stringWithFormat:@"hello %d %c",5,'A'];                //实例方法初始化(比下面两种常用)        NSString *string3 = [[NSString alloc]init];        //实例方法指定字符串        NSString *string4 = [[NSString alloc]initWithString:string3];                //实例方法创建字符串        NSString *string5 = [[NSString alloc]initWithFormat:@"%@",string4 ];</span>        

字符串获取

<span style="font-size:14px;">NSString *string6 = [NSString stringWithFormat:@"helloiphone"];                //获取字符串长度(有效字符长度，不包括'\0')        NSInteger len = [string6 length];        //字符串截取        //1.从哪个索引开始截取到字符串末尾(包含索引位置)        NSString *str0 = [string6 substringFromIndex:4];                //2.从字符串开头截取到哪个索引(不包含索引位置)        NSString *str1 = [string6 substringToIndex:8];                //3.截取一定范围(从下标3开始截取7个字符)        NSRange range = {3,7};        NSString *str2 = [string6 substringWithRange:range];                /*         typedef struct _NSRange {         NSUInteger location;     //起始位置         NSUInteger length;       //表示长度         } NSRange;                  */                //获取某字符串所在区间        NSString *string9 = @"ll";        NSRange rang1 = [string6 rangeOfString:string9];        NSRange rang2 = [string6 rangeOfString:@"pho"];        NSLog(@"************所在范围%@",NSStringFromRange(rang1));                if (rang2.location == NSNotFound) {            NSLog(@"没有这个子串");        }else{            NSLog(@"--------所在范围%@",NSStringFromRange(rang2));        }        if (rang1.length == 0) {            NSLog(@"没有这个子串");        }</span>

字符串比较

  <span style="font-size:14px;">NSString *string7 = @"ahanweilong";        NSString *string8 = @"shanweilong";        //比较地址        if (string7 == string8) {                    }                //比较内容        if ([string7 isEqualToString:string8]) {            NSLog(@"一样的~~");        }else{            NSLog(@"不一样~~");        }                        if ([string7 compare:string8] == NSOrderedSame) {            NSLog(@"相等");        }        else if ([string7 compare:string8] == NSOrderedAscending)        {            NSLog(@"升序");        }        else if ([string7 compare:string8] == NSOrderedDescending)        {            NSLog(@"降序");        }                    //NSCaseInsensitiveSearch 忽略大小写(@“123”，@“0123”字符串比较)    //NSNumericSearch 用于数值类型的比较（@“123”，@“0123”转化成数值比较）       NSComparisonResult result = [string7 compare:string8 options:NSCaseInsensitiveSearch];        if (result == NSOrderedSame) {            NSLog(@"相等");        }else if (result == NSOrderedAscending){            NSLog(@"升序");        }else if (result == NSOrderedDescending){            NSLog(@"降序");        }    }</span>

//检测字符是否以指定内容开头    if ([string7 hasPrefix:@"shan"]) {        NSLog(@"是的");    }        //检测字符串是否已指定内容结尾    if ([string7 hasSuffix:@"long"]) {        NSLog(@"是的");    }    

//字符串拼接    NSString *string10 = [string7 stringByAppendingString:string8];    NSString *string11 = [NSString stringWithFormat:@"%@%@",string7,string8];        NSString *string12 = [string7 stringByAppendingFormat:@"-%@",string11];        //将数字字符串转换为数字（最常用）    NSString *string13 = @"123";    NSInteger integer = [string13 integerValue];        //字符串大写    NSString *string14 = @"fdjfep";    NSString *str14 = [string14 uppercaseString];        //字符串小写    NSString *string15 = @"GKHgIP";    NSLog(@"%@",[string15 lowercaseString]);        //首字母大写    NSLog(@"%@",[string14 capitalizedString]);        //替换    NSString *string16 = @"文艺青年";    string16 = [string16 stringByReplacingOccurrencesOfString:@"文艺" withString:@"2B"];        //删除原字符串中的所有指定字符   NSString * string18 = [string16 stringByReplacingOccurrencesOfString:@"文" withString:@""];            //从下标0开始2个   NSString *string17 = [string16 stringByReplacingCharactersInRange:NSMakeRange(0, 2) withString:@"二傻子"];        NSRange rang = [string16 rangeOfString:@"文艺"];    string17 = [string16 stringByReplacingCharactersInRange:rang withString:@"哈哈哈"];            //去掉两端空格    string18 = [string7 stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceCharacterSet]];            //C语言字符串转化成OC字符串    NSString *str20 = [NSString stringWithCString:"hehe" encoding:NSUTF8StringEncoding];    //OC语言字符串转化成C字符串    const char *cStr = [string8 cStringUsingEncoding:NSUTF8StringEncoding];

#pragma mark - 可变字符串    //一个字符串需要经常改变，就用NSMutableString    //Capacity表示容量,可以容纳多少字符，如果字符超过存储空间就扩展（尽量开辟时就够用,也不要太大）    NSMutableString *mutableString = [NSMutableString stringWithCapacity:6];        //类方法创建可变字符串    NSMutableString *mutableString1 = [NSMutableString string];            //在指定位置插入一个字符串对象（在第一个字符串后插入）    NSString *string1 = @"长得白";    NSMutableString * mutableString2 = [NSMutableString stringWithFormat:@"闪龙"];    [mutableString2 insertString:string17 atIndex:1];    NSLog(@"%@",mutableString2);        //删除字符串中某范围内容(从第0个删除3个)    [mutableString2 deleteCharactersInRange:NSMakeRange(0, 3)];    NSRange rang3 = {2,3};    [mutableString2 deleteCharactersInRange:rang3];    NSLog(@"%@",mutableString2);        //拼接可变字符串    NSString *string2 = @"拼了";    [mutableString2 appendString:string2];    [mutableString2 appendFormat:@"老夫和你%@",string2];    NSLog(@"%@",mutableString2);        //替换    [mutableString1 deleteCharactersInRange:rang3];        NSRange rrr = [mutableString1 rangeOfString:@"df"];    [mutableString2 replaceCharactersInRange:rrr withString:@"www"];        [mutableString2 replaceOccurrencesOfString:@"iiiiihj" withString:@"小白" options:NSLiteralSearch range:rrr];        //可变字符串赋值    NSMutableString *mutableString3 = [NSMutableString stringWithCapacity:0];    //NSMutableString *mutableString3 = [NSMutableString string];    [mutableString3 setString:@"树上蹲个

UTF8 编码

NSString *name =  [self.gameModel.title stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding];

ios9.3之后

urlStr = [urlStr stringByAddingPercentEncodingWithAllowedCharacters:[NSCharacterSet URLQueryAllowedCharacterSet]];

unicode编码转中文

msg = [NSString stringWithCString:[msg cStringUsingEncoding:NSUTF8StringEncoding] encoding:NSNonLossyASCIIStringEncoding];