IOS开发笔记（8）Foundation Kit 学习

最新推荐文章于 2021-01-04 21:54:40 发布

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最新推荐文章于 2021-01-04 21:54:40 发布

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http://blog.youkuaiyun.com/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）。

[plain] view plain copy print ?

// 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);
}

 // 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"