Objective-C字符串 - 芒果文档

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📜 Objective-C字符串

📅 最后修改于: 2020-11-03 15:56:38 🧑 作者: Mango

使用NSString表示Objective-C编程语言中的字符串，其子类NSMutableString提供了几种创建字符串对象的方法。创建字符串对象的最简单方法是使用Objective-C @“ …”构造-

NSString *greeting = @"Hello";

下面显示了一个创建和打印字符串的简单示例。

现场演示

#import 

int main () {
   NSString *greeting = @"Hello";
   NSLog(@"Greeting message: %@\n", greeting );

   return 0;
}

当上面的代码被编译和执行时，产生的结果如下：

2013-09-11 01:21:39.922 demo[23926] Greeting message: Hello

Objective-C支持多种用于处理字符串的方法-

Sr.No.	Method & Purpose
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.

以下示例利用了上述几个功能-

现场演示

#import 

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 :  %d\n", len );

   /* InitWithFormat */
   str3 = [[NSString alloc] initWithFormat:@"%@ %@",str1,str2];    
   NSLog(@"Using initWithFormat:   %@\n", str3 );
   [pool drain];

   return 0;
}

当上面的代码被编译和执行时，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

您可以在《 NSString类参考》中找到与Objective-C NSString相关的方法的完整列表。