Foundation框架字符串

1)了解Foundation框架:

  Foundation框架它提供了字符串、集合、I/O等很多和其他语言一样的标准库一样的功能。

  Foundation本身就是一个巨大的库,这里无法罗列出Foundation提供的每个雷和方法。

2)Foundation框架使用字符串:

  NSString 的快捷语法:

1 NSString *someString = @"this is a string";

本质上,编译器一旦遇到@并紧跟着包含在“”之中的字符串就会创建一个静态的包含所提供字符串的NSString对象。

在比较一个字符串和另一个实例时,可以用-isEqual:

1 NSString *string1 = @"this is a string";
2 NSString *string2 = @"this is a string";//和string1相同
3 NSString *string3 = [NSString stringWithString:string:string1];
4 
5 assert(string 1 == string2);//
6 assert(string 1 isEqual:string2);//
7 assert(string 1 == string3);//

 

NSLog的格式化字符串:

NSLog(@"The age of the employee named %@ is %ld",[employee name],[employee age]);

 

使用格式化字符串:

NSString *str;

NSString *cardName = @"Ace";
NSString *cardSuit = @"Spades";

str = [NSString stringWithFormat:@"The winning card is %@ of %@.",]cardName,cardSuit;
//现在str是The winning card is Aceof Spades.

str = [NSString stringwithFormat:@"You have %ld gold",[player goldAmount]];

//现在str是You have 1000 gold

str = [NSString stringwithFormat:@"Your change is: $%.2f.",change];
//现在str是Your change is: $2.43.

 

 

OC中常见的格式说明符:

int                %d

unsigned int           %u

long               %ld

unsigned long            %lu

float                %f

NSObject子类实例        %@

 

 

NSMutableString(可变字符串)

  NSMutableString继承与NSString,所以我们可以使用NSString字符串的创建方式来创建NSMutableString。

NSString和NSMutableString的区别:

NSString是一个常量字符串,里面的值并不能更改,而NSMutableString是一个可变的字符串,字符串的值可以更改。

 1 #import <Foundation/Foundation.h>
 2 
 3 int main(int argc, const char * argv[]) {
 4     @autoreleasepool {
 5                 
 6         
 7         NSMutableString *ms1 = [NSMutableString stringWithString:@"Foundation Learing"] ;
 8         [ms1 appendString:@" Class"] ;
 9         NSLog(@"%@" , ms1) ;
10         
11         NSRange range = [ms1 rangeOfString:@" Class"] ;
12         [ms1 deleteCharactersInRange:range] ;
13         NSLog(@"%@" , ms1) ;
14 
15         
16     }
17     return 0;
18 }
19 
20 //Foundation Learing Class
21 //Foundation Learing

 

 

 

posted @ 2015-07-03 00:25  预估计  阅读(177)  评论(0编辑  收藏  举报