OC字符串

创建字符串对象

NSString *str = @”hello world”;
//从C的字符串创建一个字符串对象
NSString *str2 = [[NSString alloc] initWithUTF8String:”tian qi bu cuo o”];
NSString *str2 = [NSString
stringWithUTF8String:”tian qi bu cuo o”];
//从其他数据生成字符串对象
NSString *str3 = [[NSString alloc] initWithFormat:@”zhangsan %d %c”,age,sex];
//从另外一个字符串对象,创建字符串对象
NSString *str4 = [[NSString alloc] initWithString:str3];

计算长度

long length=[str length]

比较字符串

BOOL a=[str1 isEqualToString str2];
int r=[str1 compare str2];

查找子串

NSRstring range=[str rangeOfString substr];

提取字符和字符串

unichar c=[str characterAtInder :4]
NSString *subetring=[str substringWithRange:range];

转换

int num=[str intValue]

从文件生成字符串

NSString *str10=@”/Users/student/Desktopdict.txt”;
NSString *f=[[NSString alloc]initWithContentsOfFile:str10 encoding:NSUTF8StringEncoding error:
nil];

==NSMutableString==

<1> 创建对象
<2> 复制(设置字符串)
<3> 连接(附加)
<4> 插入
<5> 删除
<6> 替换

== 字符串处理相关

<1> 字符串分割 , 使用NSString的componentsSeparatedByString
NSArray *arr = [str componentsSeparatedByString:@” “];
<2> 数组合并为字符串 ,使用NSArray的componentsJoinedByString
NSString *comStr = [arr componentsJoinedByString:@”—“];