IOS开发笔记（8）Foundation Kit 学习



http://blog.csdn.net/xiaofansong/article/details/8423630

//“==”运算符只判断两个字符串的指针数值，而不是它们所指的对象，以下例子请区别：

NSString *thing1 = @"hello,8";

NSString *thing2 = [NSString stringWithFormat:

@"hello,%d",8];

if ([thing1 isEqual: thing2]){

NSLog(@"Yes,they are the same.");

} else {

NSLog(@"NO,they are not the same.");

}

if (thing1 == thing2){

NSLog(@"thing1 == thing2");

} else{

NSLog(@"thing1 != thing2");

}

输出：

2012-12-24 09:42:36.345 Kit学习[459:403] Yes,they are the same.

2012-12-24 09:42:36.345 Kit学习[459:403] thing1 != thing2

2.集合
集合类：NSArray 、NSDictionary

1）NSArray
NSArray是Cocoa的一个类，用来存储对象的有序列表，可以在NSArray中放入任意类型的对象。
NSArray中只能存储Objective-C的对象，而不能存储C语言中的基本数据类型，如int，float，enum，struct，或者NSArray中的随机指针。同时，也不能在NSArray中存储nil（对象的零值或NULL值）。

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1. // 创建数组 arrayWithObjects:  
2.        NSMutableArray *array;  
3.        array = [NSArray arrayWithObjects:  
4.                 @"one", @"two", @"three", nil]; //列表结尾添加nil表示列表结束  
5.          
6.        // 获取对象个数 count:  
7.        NSLog(@" the count of array is: %ld",[array count]);  
8.          
9.        // 获取特定索引处的对象 objectAtIndex:  
10.        int i;  
11.        for (i = 0 ; i < [array count]; i++)  
12.        {  
13.            NSLog(@"index %d has %@",  
14.                  i,[array objectAtIndex:i]);  
15.        }  
16.          
17.        // 将字符串切分成数组 componentsSeparatedByString:  
18.        NSString *str = @"oop : ack : elf : com : cn : net";  
19.        NSArray *arr = [str componentsSeparatedByString:@" : "];  
20.        NSLog(@"str is : %@",str);  
21.        NSLog(@"arr is :");  
22.        for (NSString *s in arr)  
23.        {  
24.            NSLog(@"\"%@\"",s);  
25.        }  
26.        // 合并数组并创建字符串 componentsJoinedByString:  
27.        NSLog(@"合并数组到NSArray.");  
28.        str = [arr componentsJoinedByString:@" $"];  
29.        NSLog(@"str is : %@",str);  
30.        NSLog(@"arr is :");  
31.        for (NSString *s in arr)  
32.        {  
33.            NSLog(@"\"%@\"",s);  
34.        }  

 // 创建数组 arrayWithObjects:        NSMutableArray *array;        array = [NSArray arrayWithObjects:                 @"one", @"two", @"three", nil]; //列表结尾添加nil表示列表结束                // 获取对象个数 count:        NSLog(@" the count of array is: %ld",[array count]);                // 获取特定索引处的对象 objectAtIndex:        int i;        for (i = 0 ; i < [array count]; i++)        {            NSLog(@"index %d has %@",                  i,[array objectAtIndex:i]);        }                // 将字符串切分成数组 componentsSeparatedByString:        NSString *str = @"oop : ack : elf : com : cn : net";        NSArray *arr = [str componentsSeparatedByString:@" : "];        NSLog(@"str is : %@",str);        NSLog(@"arr is :");        for (NSString *s in arr)        {            NSLog(@"\"%@\"",s);        }        // 合并数组并创建字符串 componentsJoinedByString:        NSLog(@"合并数组到NSArray.");        str = [arr componentsJoinedByString:@" $"];        NSLog(@"str is : %@",str);        NSLog(@"arr is :");        for (NSString *s in arr)        {            NSLog(@"\"%@\"",s);        }

输出结果

2012-12-24 10:22:56.310 Kit学习[688:403] index 0 has one

2012-12-24 10:22:56.311 Kit学习[688:403] index 1 has three

2012-12-24 10:22:56.312 Kit学习[688:403]  the count of array is: 3

2012-12-24 10:22:56.312 Kit学习[688:403] index 0 has one

2012-12-24 10:22:56.313 Kit学习[688:403] index 1 has two

2012-12-24 10:22:56.313 Kit学习[688:403] index 2 has three

2012-12-24 10:22:56.314 Kit学习[688:403] str is : oop : ack : elf : com : cn : net

2012-12-24 10:22:56.314 Kit学习[688:403] arr is :

2012-12-24 10:22:56.315 Kit学习[688:403] "oop"

2012-12-24 10:22:56.315 Kit学习[688:403] "ack"

2012-12-24 10:22:56.315 Kit学习[688:403] "elf"

2012-12-24 10:22:56.316 Kit学习[688:403] "com"

2012-12-24 10:22:56.316 Kit学习[688:403] "cn"

2012-12-24 10:22:56.317 Kit学习[688:403] "net"

2012-12-24 10:22:56.317 Kit学习[688:403]合并数组到NSArray.

2012-12-24 10:22:56.318 Kit学习[688:403] str is : oop $ack $elf $com $cn $net

2012-12-24 10:22:56.318 Kit学习[688:403] arr is :

2012-12-24 10:22:56.333 Kit学习[688:403] "oop"

2012-12-24 10:22:56.334 Kit学习[688:403] "ack"

2012-12-24 10:22:56.334 Kit学习[688:403] "elf"

2012-12-24 10:22:56.335 Kit学习[688:403] "com"

2012-12-24 10:22:56.335 Kit学习[688:403] "cn"

2012-12-24 10:22:56.336 Kit学习[688:403] "net"