Objective-C NSString/字符串
在Objective-C編程語言的字符串表示使用NSString 和它的子類NSMutableString的創建字符串對象提供了幾種方法。創建一個字符串對象最簡單的方法是使用 Objective-C 的@"..."構造：
NSString *greeting = @"Hello";
一個簡單的例子，用於創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行時，它產生的結果如下：
2013-09-11 01:21:39.922 demo[23926] Greeting message: Hello
Objective-C的支持範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行時，它產生的結果如下：
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相關方法 NSString 類參數.