OC语言基础之NSString

1.字符串的创建

   1:   NSString *s1 = @"jack";
   2:      
   3:      //NSString *s2 = [[NSString alloc] initWithString:@"jack"];
   4:      
   5:      NSString *s3 = [[NSString alloc] initWithFormat:@"age is %d", 10];
   6:      
   7:      // C字符串 --> OC字符串
   8:      NSString *s4 = [[NSString alloc] initWithUTF8String:"jack"];
   9:      // OC字符串 --> C字符串
  10:      const char *cs = [s4 UTF8String];
  11:      
  12:      // NSUTF8StringEncoding 用到中文就可以用这种编码
  13:      NSString *s5 = [[NSString alloc] initWithContentsOfFile:@"/Users/apple/Desktop/1.txt" encoding:NSUTF8StringEncoding error:nil];
  14:      

 

 

 

   1:  /*
   2:       一般都会有一个类方法跟对象方法配对
   3:       [NSURL URLWithString:<#(NSString *)#>];
   4:       [NSString stringWithFormat:@""];
   5:       [NSString stringWithContentsOfFile:<#(NSString *)#> encoding:<#(NSStringEncoding)#> error:<#(NSError *__autoreleasing *)#>];
   6:  
   7:       */

 

2.常用方法

1)检查前缀

   1:   NSString *str = @"qq=12344&pwd=adadfs";
   2:      [str hasPrefix:@"qq="];
   3:      
   4:      [str hasSuffix:@"fs"];

2)大小写转换

   1:      NSString *str = [@"adbDAd" lowercaseString];
   2:      NSString *upStr = [str uppercaseString];
   3:      NSLog(@"%@", upStr);
   4:      //    [[@"adbDAd" lowercaseString] isEqualToString:@"adsfasd"];

 

3)可变字符串

   1:     NSMutableString *str = [[NSMutableString alloc] initWithCapacity:0];
   2:      
   3:      [str appendFormat:@"123"];  //123
   4:      //    NSLog(@"%@", str);
   5:      //
   6:      //    NSString *str1 = @"123";
   7:      //    NSString *str2 = [str1 stringByAppendingString:@"aaaa"];
   8:      //    NSLog(@"%@", str2);
   9:      //
  10:      NSRange rang3 = [str rangeOfString:@"3"];
  11:      [str deleteCharactersInRange:rang3];
  12:      NSLog(@"%@", str);
  13:      
  14:      [str insertString:@"aaa" atIndex:0];
  15:      
  16:      // @"3" @""
  17:      [str replaceOccurrencesOfString:@"3"
  18:                           withString:@""
  19:                              options:NSLiteralSearch
  20:                                range:NSMakeRange(0, str.length)];
  21:      NSLog(@"%@", str);
posted @ 2015-03-06 18:18  有奈了  阅读(205)  评论(0编辑  收藏  举报