iOS学习路之Objective-C（二）—— 字符串

浏览数：29 / 时间：2015年06月11日

NSString对象的创建

 1     //创建不可变字符串
 2     NSString *string1 = @"bei jing huan ying nin";
 3 #pragma mark 对象方法创建字符串
 4     //用另一个字符串初始当前字符串，指针所指地址相同
 5     NSString *string2 = [[NSString alloc] initWithString:string1];
 6     //将其他的数据类型转化为字符串类型
 7     NSString *string3 = [[NSString alloc] initWithFormat:@"age is %d, name is %@", 23, @"DYK"];
 8 #pragma mark 类方法创建字符串
 9     //该方法与initWithString方法对应
10     NSString *string4 = [NSString stringWithString:string1];
11     //该方法与initWithFormat方法对应
12     NSString *string5 = [NSString stringWithFormat:@"age is %d, name is %@", 23, @"DYK"];

字符串的拼接

1     NSString *string1 = @"DYK";
2     NSString *string2 = @"shuai";
3     //- (NSString *)stringByAppendingString:(NSString *)aString;
4     //作用：将两个字符串进行拼接
5     //两个拼接的字符串都没有变，返回值是拼接后的字符串
6     NSString *string3 = [string1 stringByAppendingString:string2];
7     NSString *string4 = [NSString stringWithFormat:@"%@%@", string1, string2];

计算字符串的长度

1     NSString *string = @"zhou dong yu";
2     NSUInteger len = [string length];

取出字符串中成员的引用

1     NSString *string = @"zhou dong yu";
2     NSUInteger position = 0;
3     char character = [string characterAtIndex:position];

字符串的比较

 1     NSString *string1 = @"chen chao";
 2     NSString *string2 = @"CHAN CHAO";
 3 #if 0
 4     //- (BOOL)isEqualToString:(NSString *)aString;
 5     //作用：比较两个字符串是否完全相同
 6     //BOOL：YES(真), NO(假)
 7     BOOL bl = [string1 isEqualToString:string2];
 8     if (bl) {
 9         NSLog(@"string1 == string2");
10     } else{
11         NSLog(@"string1 != string2");
12     }
13 #endif
14     
15 #if 0
16     //- (NSComparisonResult)compare:(NSNumber *)decimalNumber;
17     //作用：比较两个字符串是否相同(不忽略大小写)
18     //NSComparisonResult:NSOrderedAscending(升序)
19     //                   NSOrderedSame(相同)
20     //                   NSOrderedDescending(降序)
21     NSComparisonResult result = [string1 compare:string2];
22     if (result == NSOrderedDescending) {
23         NSLog(@"string1 < string2");
24     } else if (result == NSOrderedAscending) {
25         NSLog(@"string1 > string2");
26     } else {
27         NSLog(@"string1 == string2");
28     }
29 #endif
30     //- (NSComparisonResult)caseInsensitiveCompare:(NSString *)string;
31     //作用：比较两个字符串是否相同(忽略大小写)
32     NSComparisonResult result = [string1 caseInsensitiveCompare:string2];
33     if (result == NSOrderedDescending) {
34         NSLog(@"string1 < string2");
35     } else if (result == NSOrderedAscending) {
36         NSLog(@"string1 > string2");
37     } else {
38         NSLog(@"string1 == string2");
39     }

在字符串中查找子串的位置

 1     NSString *string1 = @"chen chao zui shuai";
 2     NSString *string2 = @"zui";
 3     
 4     //- (NSRange)rangeOfString:(NSString *)aString;
 5     //作用：在一个字符串中查找子串的位置
 6     //typedef struct _NSRange {
 7     //    NSUInteger location;  起始位置
 8     //    NSUInteger length;    从起始位置开始的长度
 9     //} NSRange;
10     NSRange range = [string1 rangeOfString:string2];
11     if (range.location == NSNotFound) {
12         NSLog(@"没有找到");
13     }
14     NSLog(@"location is %lu, length is %lu", range.location, range.length);