ios学习笔记－－（oc基础3）

NSString和NSMutableString的常见用法

1.NSString

1.1定义并初始化字符串

4种方法

NSString *str1=@"asdfghj";
NSString *str2 = [[NSString alloc]initWithFormat:@"this is a string"];
NSString *str3 = [NSString stringWithFormat:@"hello"];
//str4 可以用于NSString转NSMutableString
NSString *str4 = [NSString stringWithString:@"hello"];

1.2 c中的字符串转NSString

char *str ="hello";
NSString *newstr = [NSString stringWithUTF8String:str];
char *str ="hello";
NSString *newstr = [NSString alloc]initWithCString:<#(const char *)#> encoding:<#(NSStringEncoding)#>;

1.3 比较字符串的大小

1.3.1地址的比较 用基本的比较运算符 alloc 存在堆中 @“11”存放常量区

1.3.2内容的比较

BOOL isEqualToString =  [str6 isEqualToString:str7];

[str2 compare:<#(NSString *)#> options:<#(NSStringCompareOptions)#>];

1.4字符转换

[str1 uppercaseString]；
[str1 lowercaseString]；
[str1 capitalizedString]；
[num intValue];

1.5字符串的截取

[str1 substringFromIndex:2];
[str1 substringToIndex:4]
[str1 substringWithRange:range];

NSRange range1= [str1 rangeOfString:str33];

NSStringFromRange(range1)／／将range1转化成字符串

1.6增加前辍和后缀

[url hasSuffix:@".com"];//bool 如果有这个后缀

1.7字符串的追加

[http stringByAppendingString:url];／／追加字符串

1.8字符串的替换

NSString *newCompany=[newUrl stringByReplacingCharactersInRange:range withString:@"taobao"];

2.可变字符串

appendString

insertString

appendFormat

deleteCharactersInRange

replaceCharacterInrage