Objective-C用到次数多的NSString methods

1. NSString *str1 = @"BeiJing";

2.     NSString *str2 = @"beijing";
3.     
   
4.     //全部转为大写
5.     NSLog(@"%@",[str1 uppercaseString]);
6.     //全部转为小写
7.     NSLog(@"%@",[str1 lowercaseString]);
8.     
   
9.     //首字母大写
10.     NSLog(@"%@",[str1 capitalizedString]);
11.     
    
12.     //比较两个字符串内容是否相同
13.     BOOL b =[str1 isEqualToString:str2];
14.     
    
15.     //两个字符串内容比较
16.     //NSOrderedAscending    右边 > 左边
17.     //NSOrderedSame         内容相同
18.     //NSOrderedDescending   左边 > 右边
19.     NSComparisonResult result = [str1 compare:str2];
20.     if (result == NSOrderedAscending) {
21.         NSLog(@"右边 > 左边");
22.     }else if(result == NSOrderedSame){
23.         NSLog(@"内容相同");
24.     }else if (result == NSOrderedDescending){
25.         NSLog(@"左边 > 右边");
26.     }
27.     
    
28.     //忽略大小写进行比较，返回值与compare一样
29.     result = [str1 caseInsensitiveCompare:str2];
30.     if (result == NSOrderedAscending) {
31.         NSLog(@"右边 > 左边");
32.     }else if(result == NSOrderedSame){
33.         NSLog(@"内容相同");
34.     }else if (result == NSOrderedDescending){
35.         NSLog(@"左边 > 右边");
36.     }
37.     
    
38.     //判断字符串是否以指定字符串开头
39.     [str1 hasPrefix:@"aaa"];
40.     //判断字符串是否以指定字符串结尾
41.     [str1 hasSuffix:@"aaa"];
42.     
    
43.     //判断字符串是否包含指定字符串，返回位置和长度
44.     NSRange range = [@"123456" rangeOfString:@"456"];
45.     NSLog(@"%@", NSStringFromRange(range));
46.     
    
47.     //反向搜索
48.     range = [@"123456456qweasasd456" rangeOfString:@"456" options:NSBackwardsSearch];
49.     NSLog(@"%@",NSStringFromRange(range));
50.     
    
51.     //指定范围进行搜索
52.     range = NSMakeRange(0, 9);
53.     range = [@"123456456qweasasd456" rangeOfString:@"456" options:NSBackwardsSearch range:range];
54.     NSLog(@"%@",NSStringFromRange(range));
55. 
    
    
58.        
     
59.                
     
60.                        
    
    
61.                         
    
62.                
63.        
66.         NSString *str = @"123456789";
67.         NSLog(@"%@",[str substringFromIndex:3]);
68.         NSLog(@"%@",[str substringToIndex:6]);
69.         NSLog(@"%@",[str substringWithRange:NSMakeRange(3, 3)]);
70.         
71.         //用指定字符串分割字符串，返回一个数组
72.         NSArray *array = [@"1,2,3,4,5,6" componentsSeparatedByString:@","];
73.         NSLog(@"%@",array);
74.         
75.         //将数组中的字符串组合成一个文件路径
76.         NSMutableArray *components = [NSMutableArray array];
77.         [components addObject:@"Users"];
78.         [components addObject:@"CentralPerk"];
79.         [components addObject:@"Desktop"];
80.         NSString *path = [NSString pathWithComponents:components];
81.         NSLog(@"%@",path);  //Users/CentralPerk/Desktop
82.         
83.         //将一个路径分割成一个数组
84.         NSArray *array1 = [path pathComponents];
85.         NSLog(@"%@",array1);
86.         
87.         //判断是否为绝对路径(依据：是否以‘/‘开始)
88.         path = @"/Users/CentralPerk/Desktop";
89.         NSLog(@"%i",[path isAbsolutePath]);
90.         
91.         //获取最后一个目录
92.         NSLog(@"%@",[path lastPathComponent]);
93.         
94.         //删除最后一个目录
95.         NSLog(@"%@",[path stringByDeletingLastPathComponent]);
96.         
97.         //拼接一个目录
98.         NSLog(@"%@",[path stringByAppendingPathComponent:@"aaa"]);   ///Users/CentralPerk/Desktop/aaa
99.         NSLog(@"%@",[path stringByAppendingString:@"aaa"]);      ///Users/CentralPerk/Desktopaaa
100.         NSLog(@"%@",[path stringByAppendingFormat:@"%@%@",@"b",@"c"]);  ///Users/CentralPerk/Desktopbc
101.         
102.         //拓展名出来
103.         //获取拓展名,不带.
104.         NSString *str2 = @"Users/CentralPerk/Desktop/test.txt";
105.         NSLog(@"%@",[str2 pathExtension]);
106.         //添加拓展名,不需要带.
107.         NSLog(@"%@",[str2 stringByAppendingPathExtension:@"mp3"]);
108.         //删除拓展名,带.一块删除
109.         NSLog(@"%@",[str2 stringByDeletingPathExtension]);
110.         
111.         //字符串转为 int double float
112.         NSString *str3 = @"123";
113.         NSLog(@"%i",[str3 intValue]);
114.         NSLog(@"%zi",[str3 length]);
115.         
116.         //取出指定位置的字符
117.         unichar c = [str3 characterAtIndex:2];
118.         NSLog(@"%c",c);
119.         
120.         //转为C语言的字符串
121.         const char *s = [str3 UTF8String];
122.         NSLog(@"%s",s);
124. 
     
     

Objective-C用到次数多的NSString methods

原文：http://www.cnblogs.com/Angusge/p/4928959.html