1 1、创建常量字符串
2 NSString *str = @"Hello World!";
3
4 2、创建空字符串，给予赋值
5 NSString *str = [[NSString alloc] init];
6 str = @"Hello World!";
7 [str release];
8
9
10 3、initWithString方法
11 NSString *str = [[NSString alloc] initWithString:@"Hello World!"];
12 [str release];
13
14 4、用标准c创建字符串:initWithCString方法
15 char *Cstr = "This is a String!";
16 NSString *str = [[NSString alloc] initWithCString:Cstr];
17 [str release];
18
19 5、创建格式化字符串:占位符%
20 int i = 1;
21 int j = 2;
22 NSString *str = [[NSString alloc] initWithString:[NSString stringWithFormat:@"%d.This is %i string!",i,j]];
23 [str release];
24
25 6、创建临时字符串
26 NSString *str = [NSString stringWithCString:"Hello World"];
27
28 7、从文件创建字符串
29 NSString *path = [[NSBundlemainBundle] pathForResource:@"str.text"ofType:nil];
30 NSString *str = [[NSString alloc] initWithContentsOfFile:path];
31 NSLog(@"str:%@",str);
32 [str release];
33
34 8、用字符串创建字符串，并写入到文件
35 NSString *str = [[NSString alloc] initWithString:@"This is a String!"];
36 NSString *path = @"str.text";
37 [str writeToFile: path atomically: YES];
38 [str release];
39
40 9、isEqualToString方法
41 NSString *str01 = @"This is a String!";
42 NSString *str02 = @"This is a String!";
43 BOOL result = [str01 isEqualToString:str02];
44 NSLog(@"result:%d",result);
45
46 10、compare方法(comparer返回的三种值)
47 //NSOrderedSame判断两者内容是否相同
48 NSString *str01 = @"This is a String!";
49 NSString *str02 = @"This is a String!";
50 BOOL result = [str01 compare:str02] == NSOrderedSame;
51 NSLog(@"result:%d",result);
52
53 //NSOrderedAscending判断两对象值的大小(按字母顺序进行比较，astring02大于astring01为真)
54 NSString *str01 = @"This is a String!";
55 NSString *str02 = @"this is a String!";
56 BOOL result = [str01 compare:str02] == NSOrderedAscending;
57 NSLog(@"result:%d",result);
58
59 //NSOrderedDescending判断两对象值的大小(按字母顺序进行比较，astring02小于astring01为真)
60 NSString *str01 = @"this is a String!";
61 NSString *str02 = @"This is a String!";
62 BOOL result = [str01 compare:str02] == NSOrderedDescending;
63 NSLog(@"result:%d",result);
64
65 11、不考虑大小写比较字符串
66 NSString *str01 = @"this is a String!";
67 NSString *str02 = @"This is a String!";
68 BOOL result = [str01 caseInsensitiveCompare:str02] == NSOrderedSame; //NSOrderedDescending判断两对象值的大小(按字母顺序进行比较，str02小于str01为真)
69 NSLog(@"result:%d",result);
70
71 NSString *str01 = @"this is a String!";
72 NSString *str02 = @"This is a String!";
73 BOOL result = [str01 compare:str02
74
75 options:NSCaseInsensitiveSearch | NSNumericSearch] == NSOrderedSame;
76 NSCaseInsensitiveSearch:不区分大小写比较 NSLiteralSearch:进行完全比较，区分大小写 NSNumericSearch:比较字符串的字符个数，而不是字符值。
77 NSLog(@"result:%d",result);
78
79 12、输出大写或者小写字符串
80 NSString *string1 = @"String";
81
82 NSString *string2 = @"String";
83
84 NSLog(@"string1:%@",[string1 uppercaseString]);//大写
85
86 NSLog(@"string2:%@",[string2 lowercaseString]);//小写
87
88 NSLog(@"string2:%@",[string2 capitalizedString]);//首字母大小
89
90 13、-rangeOfString: 查找字符串某处是否包含其它字符串
91 NSString *string1 = @"This is a string";
92 NSString *string2 = @"string";
93 NSRange range = [string1 rangeOfString:string2];
94 int location = range.location;
95 int leight = range.length;
96 NSString *str = [[NSString alloc] initWithString:[NSString stringWithFormat:@"Location:%i,Leight:%i",location,leight]];
97 NSLog(@"str:%@",str);
98 [str release];
99
100 14、-substringToIndex: 从字符串的开头一直截取到指定的位置，但不包括该位置的字符
101 NSString *string1 = @"This is a string";
102 NSString *string2 = [string1 substringToIndex:3];
103 NSLog(@"string2:%@",string2);
104
105 15、-substringFromIndex: 以指定位置开始（包括指定位置的字符），并包括之后的全部字符
106 NSString *string1 = @"This is a string";
107 NSString *string2 = [string1 substringFromIndex:3];
108 NSLog(@"string2:%@",string2);
109
110 16、-substringWithRange: 按照所给出的位置，长度，任意地从字符串中截取子串
111 NSString *string1 = @"This is a string";
112 NSString *string2 = [string1 substringWithRange:NSMakeRange(0, 4)];
113 NSLog(@"string2:%@",string2);
114
115 17、-stringWithCapacity: 按照固定长度生成空字符串
116 NSMutableString *String;
117 String = [NSMutableString stringWithCapacity:20];
118
119 18、-appendString: and -appendFormat: 把一个字符串接在另一个字符串的末尾
120 NSMutableString *str1 = [[NSMutableString alloc] initWithString:@"This is a NSMutableString"];
121
122 [str1 appendString:@", I will be adding some character"];
123
124 [str1 appendFormat:[NSString stringWithFormat:@", I will be adding some character"]];
125
126 NSLog(@"str1:%@",str1);
127
128 19、-insertString: atIndex: 在指定位置插入字符串
129 NSMutableString *str1 = [[NSMutableString alloc] initWithString:@"This is a NSMutableString"];
130
131 [str1 insertString:@"Hi! " atIndex:0];
132
133 NSLog(@"str1:%@",str1);
1 20、-setString:
2 NSMutableString *str = [[NSMutableString alloc] initWithString:@"This is a NSMutableString"];
3
4 [str setString:@"Hello Word!"];
5
6 NSLog(@"str:%@",str);
7
8
9 21、-replaceCharactersInRange: withString: 用指定字符串替换字符串中某指定位置、长度的字符串
10 NSMutableString *str = [[NSMutableString alloc] initWithString:@"This is a NSMutableString"];
11
12 [str replaceCharactersInRange:NSMakeRange(0, 4) withString:@"That"];
13
14 NSLog(@"str:%@",str);
15
16
17 22、-hasPrefix: 检查字符串是否以另一个字符串开头
18 NSString *str = @"NSStringInformation.txt";
19
20 [str hasPrefix:@"NSString"] = = 1 ? NSLog(@"YES") : NSLog(@"NO");
21
22 [str hasSuffix:@".txt"] = = 1 ? NSLog(@"YES") : NSLog(@"NO");
23
24
25 23、扩展路径
26 NSString *Path = @"~/NSData.txt";
27
28 NSString *absolutePath = [Path stringByExpandingTildeInPath];
29
30 NSLog(@"absolutePath:%@",absolutePath);
31
32 NSLog(@"Path:%@",[absolutePath stringByAbbreviatingWithTildeInPath]);
33
34
35 24、文件扩展名
36 NSString *Path = @"~/NSData.txt";
37
38 NSLog(@"Extension:%@",[Path pathExtension]);
1 // 切割所有的参数
2 NSArray *array = [str componentsSeparatedByString:@"&"];
