发布于 2015-07-05 11:48:54 | 211 次阅读 | 评论: 0 | 来源: 网络整理
在Objective-C编程语言的字符串表示使用NSString 和它的子类NSMutableString的创建字符串对象提供了几种方法。创建一个字符串对象最简单的方法是使用 Objective-C 的@"..."构造：
NSString *greeting = @"Hello";
一个简单的例子，用于创建和打印字符串如下所示。
#import <Foundation/Foundation.h>
int main ()
{
NSString *greeting = @"Hello";
NSLog(@"Greeting message: %@n", greeting );
return 0;
}
上面的代码编译和执行时，它产生的结果如下：
2013-09-11 01:21:39.922 demo[23926] Greeting message: Hello
Objective-C的支持范围广泛的操作字符串的方法：
| S.N. | 方法 & 目的 |
|---|---|
| 1 | - (NSString *)capitalizedString; Returns a capitalized representation of the receiver. |
| 2 | - (unichar)characterAtIndex:(NSUInteger)index; Returns the character at a given array position. |
| 3 | - (double)doubleValue; Returns the floating-point value of the receiver’s text as a double. |
| 4 | - (float)floatValue; Returns the floating-point value of the receiver’s text as a float. |
| 5 | - (BOOL)hasPrefix:(NSString *)aString; Returns a Boolean value that indicates whether a given string matches the beginning characters of the receiver. |
| 6 | - (BOOL)hasSuffix:(NSString *)aString; Returns a Boolean value that indicates whether a given string matches the ending characters of the receiver. |
| 7 | - (id)initWithFormat:(NSString *)format ...; Returns an NSString object initialized by using a given format string as a template into which the remaining argument values are substituted. |
| 8 | - (NSInteger)integerValue; Returns the NSInteger value of the receiver’s text. |
| 9 | - (BOOL)isEqualToString:(NSString *)aString; Returns a Boolean value that indicates whether a given string is equal to the receiver using a literal Unicode-based comparison. |
| 10 | - (NSUInteger)length; Returns the number of Unicode characters in the receiver. |
| 11 | - (NSString *)lowercaseString; Returns lowercased representation of the receiver. |
| 12 | - (NSRange)rangeOfString:(NSString *)aString; Finds and returns the range of the first occurrence of a given string within the receiver. |
| 13 | - (NSString *)stringByAppendingFormat:(NSString *)format ...; Returns a string made by appending to the receiver a string constructed from a given format string and the following arguments. |
| 14 | - (NSString *)stringByTrimmingCharactersInSet:(NSCharacterSet *)set; Returns a new string made by removing from both ends of the receiver characters contained in a given character set. |
| 15 | - (NSString *)substringFromIndex:(NSUInteger)anIndex ; Returns a new string containing the characters of the receiver from the one at a given index to the end. |
下面的示例，如何使用几个上述功能：
#import <Foundation/Foundation.h>
int main ()
{
NSString *str1 = @"Hello";
NSString *str2 = @"World";
NSString *str3;
int len ;
NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init];
/* uppercase string */
str3 = [str2 uppercaseString];
NSLog(@"Uppercase String : %@n", str3 );
/* concatenates str1 and str2 */
str3 = [str1 stringByAppendingFormat:@"World"];
NSLog(@"Concatenated string: %@n", str3 );
/* total length of str3 after concatenation */
len = [str3 length];
NSLog(@"Length of Str3 : %dn", len );
/* InitWithFormat */
str3 = [[NSString alloc] initWithFormat:@"%@ %@",str1,str2];
NSLog(@"Using initWithFormat: %@n", str3 );
[pool drain];
return 0;
}
上面的代码编译和执行时，它产生的结果如下：
2013-09-11 01:15:45.069 demo[30378] Uppercase String : WORLD
2013-09-11 01:15:45.070 demo[30378] Concatenated string: HelloWorld
2013-09-11 01:15:45.070 demo[30378] Length of Str3 : 10
2013-09-11 01:15:45.070 demo[30378] Using initWithFormat: Hello World
可以找到一个完整的列表Objective-C中的NSString相关方法 NSString 类参数.