Objective-C教學
Objective-C 教學首頁
Objective-C 語言概述
Objective-C 開發環境(安裝配置)
Objective-C語言程序結構
Objective-C 基本語法
Objective-C 數據類型
Objective-C 變量
Objective-C 常量
Objective-C 運算符
Objective-C 算術運算符
Objective-C 關係運算符
Objective-C 邏輯運算符
Objective-C 位運算符
Objective-C 賦值運算符
Objective-C 循環
Objective-C while循環
Objective-C for循環
Objective-C do...while循環
Objective-C 嵌套循環
Objective-C break語句
Objective-C continue語句
Objective-C 決策
Objective-C if語句
Objective-C if...else 語句
Objective-C 嵌套 if 語句
Objective-C switch語句
Objective-C 嵌套switch語句
Objective-C 函數
Objective-C 函數按值調用
Objective-C 函數引用調用
Objective-C 塊
Objective-C Numbers/數字
Objective-C Arrays/數組
Objective-C 多維數組
Objective-C 數組作爲函數參數傳遞
Objective-C 從函數返回數組
Objective-C 指針的數組
Objective-C 指針
Objective-C 指針運算
Objective-C 數組的指針
Objective-C 指向指針的指針
Objective-C 傳遞函數的指針
Objective-C 函數返回指針
Objective-C NSString/字符串
Objective-C struct/結構
Objective-C 預處理器
Objective-C typedef
Objective-C 類型轉換
Objective-C 日誌處理
Objective-C 錯誤處理
命令行參數
Objective-C 類&對象
Objective-C 繼承
Objective-C 多態性
Objective-C 數據封裝
Objective-C Categories/類別
Objective-C Posing/冒充
Objective-C 擴展
Objective-C Protocols/協議
Objective-C 動態綁定
Objective-C 複合對象
Obj-C Foundation/基礎框架
Objective-C 數據存儲
Objective C 文本和字符串
Objective-C 日期和時間
Objective-C 異常處理
Objective-C 文件處理
Objective-C URL加載系統
Objective-C 快速枚舉
Objective-C 內存管理

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.