#Objective - C - Fourth-Day NSString的常用语法点总结

---

NSString为不可变字符串,NSMutableString可变更字符串(但必须初始化)

• 初始化
• 列表内容
• 字符串截取
• 字符串比较
• 字符串长度
• 字符串相等与前后缀
• 存在关系
• 字符串拼接
• 类型转换
• 字符串转换数组
• 大小写替换
• 去除字符串的符号
• 可变字符串

---

初始化

//创建字符串NSString *str1 = [NSString stringWithFormat:@"鸡.贼memem3.1415962daHHH.a"];//[NSString string];NSString *str2 = [[NSString alloc]initWithString:str1];//指定字符串初始化NSString对象NSString *str3 = [NSString stringWithFormat:@"%@,%@",str1,str2];

---

字符串截取

[str1 substringFromIndex:3];[str1 substringToIndex:2]; //从下标0开始截取[str1 substringWithRange:NSMakeRange(1, 2)];

---

字符串比较

if ([str1 compare:str3]) {        NSLog(@"不同");    }[str1 caseInsensitiveCompare:str3];//不区别大小写比较//比较输出数值NSComparisonResult result = [str1 compare:str3];    switch(result){        case NSOrderedSame:         //比较相等            NSLog(@"相同");            break;        case NSOrderedAscending:        //左边的大            NSLog(@"前大后小");            break;        case NSOrderedDescending:       //右边的大            NSLog(@"后大前小");            break;        default:            break;    }

---

字符串长度

[str3 length];

---

字符串的相等相等

字符串的前缀后缀

if ([str1 isEqualToString:str2]) {        }  //相等[str1 hasPrefix:@"鸡"];//前缀[str1 hasSuffix:@"a"];//后缀

---

存在关系

//存在关系 - (NSRange)rangeOfString:(NSString *)aString; //搜索字符串One是否存在于字符串TwoNSLog(@"%ld",[str3 rangeOfString:str1].location);//判断字符串str3是否存在于字符串str1

---

字符串拼接

[str1 stringByAppendingString:str3];[str1 stringByAppendingFormat:str2,str3];//将str2和str3拼接到str1后NSString *str = [NSString stringWithFormat:str2,str3];

---

类型转换

NSLog(@"%f",[str doubleValue]);NSLog(@"%f", [str floatValue]);NSLog(@"%d", [str intValue]);NSLog(@"%ld", [str integerValue]);NSLog(@"%lld", [str longLongValue]);NSLog(@"%d", [str boolValue]);

---

字符串转换为数组

NSString *change = @"1,2,3,4";[[change componentsSeparatedByString:@","]objectAtIndex:3];

---

大小写间转换

[str1 uppercaseString];//全大写[str1 lowercaseString];//小写[str1 capitalizedString];//首字母大写

---

去除字符串的空格和字符

[@"  saldaj " stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceCharacterSet]]; //去掉字符串最右边的一个空格NSLog(@"%@",[@"  saldaj" stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceAndNewlineCharacterSet]]);//去掉回车NSLog(@"%@",[@"110.01300" stringByTrimmingCharactersInSet:[NSCharacterSet characterSetWithCharactersInString:@"0"]]);//去掉字符串右边所有"0"

---

去除特殊符号 或任意符号

NSCharacterSet *delect = [NSCharacterSet characterSetWithCharactersInString:@"@／：；（）¥「」＂、[]{}#%-*+=_\\|~＜＞$€^•'@#$%^&*()_+'\""];NSString *strold = @"@／：；（）¥「」＂、[]{}#%-*+=_\\|~＜＞$€^•'@#$%^&*(我最帅)_+'\"";strold = [strold stringByTrimmingCharactersInSet:delect];//strnew 为删除了delect中特殊符号后 剩下保留的字符串NSLog(@"%@",strold);

---

字符串替换

NSString *string = @"夏浩文最帅啦HHHHaaaa";[string stringByReplacingOccurrencesOfString:@"夏浩文" withString:@"夏小龙"];[string stringByReplacingOccurrencesOfString:@"夏浩文" withString:@"夏小龙" options:NSCaseInsensitiveSearch range:NSMakeRange(0, 3)];//在不区别大小写比较的情况下 且从范围(下标,长度)下的 @"夏浩文"替换成@"夏小龙"[string stringByReplacingCharactersInRange:NSMakeRange(0, 3) withString:@"么么哒"];//指定从下标第0个开始三个字符串替换成@"么么哒"

---

可变字符串(必须初始化)

NSMutableString *mustr = [NSMutableString stringWithString:@"heating,too hot"];//替换[mustr replaceCharactersInRange:NSMakeRange(8, 7) withString:@"yeah! hot much!"];NSLog(@"%@",mustr);//不能直接放入nslog里使用//插入[mustr insertString:@"It's" atIndex:7];//从索引位置开始插入//删除指定区域[mustr deleteCharactersInRange:NSMakeRange(0, 7)];NSLog(@"%@",mustr);//追加(拼接)[mustr appendString:@"meemda"];[mustr appendFormat:@",%d %@",11,@"go"];//进行多个拼接NSLog(@"%@",mustr);

OC路途漫漫,努力学习