在Objective-C編程語言的字符串表示使用NSString 和它的子類NSMutableString的創(chuàng)建字符串對象提供了幾種方法。創(chuàng)建一個字符串對象最簡單的方法是使用 Objective-C 的@"..."構(gòu)造：
NSString *greeting = @"Hello";
一個簡單的例子，用于創(chuàng)建和打印字符串如下所示。
#import <Foundation/Foundation.h> int main () { NSString *greeting = @"Hello"; NSLog(@"Greeting message: %@ ", greeting ); return 0; }
上面的代碼編譯和執(zhí)行時，它產(chǎn)生的結(jié)果如下：
2013-09-11 01:21:39.922 demo[23926] Greeting message: Hello
Objective-C的支持范圍廣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-yiibai value of the receiver’s text as a double. |
| 4 |
- (float)floatValue; Returns the floating-yiibai 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，如何使用幾個上述功能：
#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 : %@ ", str3 ); /* concatenates str1 and str2 */ str3 = [str1 stringByAppendingFormat:@"World"]; NSLog(@"Concatenated string: %@ ", str3 ); /* total length of str3 after concatenation */ len = [str3 length]; NSLog(@"Length of Str3 : %d ", len ); /* InitWithFormat */ str3 = [[NSString alloc] initWithFormat:@"%@ %@",str1,str2]; NSLog(@"Using initWithFormat: %@ ", str3 ); [pool drain]; return 0; }
上面的代碼編譯和執(zhí)行時，它產(chǎn)生的結(jié)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
可以找到一個完整的列表Objective-C中的NSString相關(guān)方法 NSString 類參數(shù).
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