Foundation构架

一Foundation简介
Foundation—基础框架。框架中包含了很多开发中常用的数据类型，如结构体，枚举，类等，是其他ios框架的基础。Foundation框架中的类都是以NS为前缀(Next Step的缩写)
二Foundation常用类示例
1）NSString类
字符串比较函数：compare 它区分大小写

//示例代码NSString a = @"abc";NSString b = @"acd";NSComparisonResult  s = [a compare:b];

前后缀：hasPrefix hasSuffix

//示例代码NSString a = @"www.baidu.com";NSString b = @"xing.jpg";if ([a hasPrefix:@"www."])//返回BOOL值    NSLog(@"YES");else    NSLog(@"NO");if([b hasSuffix:@".jpg"])//返回BOOL值    NSLog(@"YES");else    NSLog(@"NO");

字符串查找：rangeOfString 查找字符串首次出现的位置

NSString a = @"www.baidu.com";NSString b = @"baidu";NSRange range = [a rangeOfString:b];NSLog(@"%lu,%lu",range.location,range.lenth);

字符串截取和替换：substringFromIndex 从index处截取到最后（包含index位置）
substringToIndxe 从头截取到index这个位置（不包含index位置）
substringWithRange //截取一个范围的字符串
stringByReplacingOcurrenceOfString: a withString b
//查找a并将a替换成b
获取每个字符串的字符：characterAtIndex: //获取在index处的字符

NSString *string = @"abcdefg";unsigned char c ;for( int i = 0 ;i < string.length; i ++){    c = [string characterAtIndex:i];    printf("%c\t",c);}

将字符串换成基本数据类型：intValue,floatValue,doubleValue

NSString *num = @"12";int number = [num intValue];NSLog(@"%d",number);

将C字符串转换成OC字符串：stringWithUTF8String

char *s = "abc";NSString *str = [NSString stringWithUTF8String:s];NSLog(@"%@",str);

将OC字符串转换成C字符串：UTF8String

NSString *str = @"abc";char *s = [str UTF8String];NSLog(@"%s",s);

可变字符串NSMutableString: 占用的空间和位置都可以改变
初始化：stringWithFormat: //用字符串进行格式化
appendString: //在尾部附加字符串
NSMutableString string //创建空可以字符串

NSMuatbleString *a = [NSMuatbleString stringWithForamt:@"abc"];[a appendString:@"def"];NSLog(@"%@",a);

可变字符串其它功能：

deleteCharactersInRange: //删除某一范围的字符串
insertString:a AtIndex: b //在索引位置b处插入字符串a
replaceCharactersInRange:a withString :b//将a范围的字符串用b替换

2）NSArray类
创建数组方法

NSArray *a1=[NSArray array]; //空数组NSArray *a2=[NSArray arrayWithObject:@"abc"];//以一个对象填充数组NSArray *a3=[NSArray arrayWithObjects:@"abc",@"def",nil];//以多个对象填充数组NSArray *a4=[[NSArray alloc] initWithObjects:@"1",@"w",nil];NSArray *a5=[NSArray arrayWithArry:a4];//以数组填充数组

数组遍历
1 是通过下标
2 是快速枚举

for(NSString *a int arr){    NSLog(@"%@",a);}

3 通过block

[arr enumerateObjectsWithBlock:^(id obj,NSUIteger idx,BOOL *stop)]{    NSLog("id = %ld,obj = %@",idx,obj);}

其它功能：
arr writeToFile:path atomically: //将数组arr的内容写到path路径的文件中
arrayWithContensOfFile:path //将路径中的文件写到数组中

可变数组NSMuableArray
创建

NSMuableArray *a1 = [NSMuableArray array];NSMuableArray *a2 = [NSMuableArray arrayWithObject:@"abc"];NSMuableArray *a3 = [NSMuableArray arrayWithObjects:@"abc",@"def",nil];NSMuableArray *a4 = [NSMuableArray arrayWithCapacity:6];

NSMuableArray 增删改查
insertObject: a AtIndex: b //在b位置插入a
removeObject:a //移除a
replaceWithObjectAtIndex: a withObject:b //用b将a替换
containsObject:a // 数组中是否包含a对象
exchangeWithObjectAtIndex:a withObjectAtIndex:b//a和了互换
3）NSDictionary类
通过 一个key，找到相应 的value；
创建对象

NSDictionary *d1 = [NSDictionary dictionary];NSDictionary *d2 = [NSDictionary dictionaryWithObject:@"1" forKey:@"2"];NSDictionary *d3 = [NSDictionary dictionaryWithObjectAndKeys:@"name1",@"1",@"name2",@"2",nil];NSDictionary *d4 = @{@"1":@"name1",@"2":@"name2"};NSLog(@"%d",d4.count);//输出字典长度NSString *str = [d4 objectWithKey:@"1"];//找到对应key的valuefor(NSString *str1 in d4)//遍历字典{NSLog(@"key = %d,value = %@",str1,[d4 objectWithKey:key]);  }//通过block遍历字典[d4 enumerateObjectsWithBlock:^(id obj,NSUIteger idx,BOOL *stop)]{    NSLog("%@ = %@",idx,obj);}

字典同样有文件操作，它类似array的文件操作。
写文件和array的名一样
读文件dictionaryWithContentsOfFile

NSMutableDictionary

//创建NSMutableDictionary *d1 = [NSMutableDictionary dictionary]；NSMutableDictionary *d2 = [NSMutableDictionary dictionaryWithCapacity:5];

//NSMutableDictionary 增删改查
setObject:a forKey:b //修改值，增加值
removeObjectForKey:a //根据a 删除value
containsObject:a //查找

4）NSFileManager文件管理类

NSFileManager *fm = [NSFileManager defaultManager];BOOL isYes = [fm fileExistsAtPath:@"//Users//Desktop//a.txt"];//判断是否是文件或目录BOOL isDir;BOOL isYes = [fm fileExistsAtPath:@"//Users//Desktop" isDirectory:&isDir]; //判断 是否是目录isYes = [fm isReadableFileAtPath:@"//Users//Desktop//a.txt" ];//判断是否可读isYes = [fm isWritableFileAtPath:@"//Users//Desktop//a.txt" ];//判断是否可写isYes = [fm isDeletableFileAtPath:@"//Users//Desktop//a.txt" ];//判断是否可删除Dictionary *dic  = [fm attributesOfItemAtPath:@"//Users//Desktop"];/获取文件属性NSArray *arr = [fm subpathsAtPath:@"//Users//Desktop"];//获取本目录及子目录NSArray *arr1 = [fm contentsOfDirectoryAtPath:@"//Users//Desktop"];//获取本目录

5）NSNumber类
它是OC中处理数值类型的一个类

    int a = 10;    float c = 3.23f;    double d = 2.34;     NSNumber *intObj = [NSNumber numberWithInt:a];//int  a-->obj     NSNumber *floatObj = [NSNumber numberWithFloat:f1];//float c -->obj     NSNumber *dObj = [NSNumber numberWithDouble:d];//double d -->obj

5）NSValue类
将结构体转换为对象

    CGPoint p1 = CGPointMake(20, 20);    NSMutableArray *arr = [NSMutableArray array];    NSValue *pointVal = [NSValue valueWithPoint:p1];//p1-->obj

6)NSDate类
日期类

NSDate *d1 = [NSDate date];//得到现在时间NSDateFormatter *formatter = [NSDateFormatter new];formatter.dateFormat = @"yyyy年MM月dd日 HH:mm:ss"; //格式化显示时间NSDate *tomorrow = [NSDate dateWithTimeIntervalSinceNow:24];//时间差方法1formatter.dateFormat = @"yyyy年MM月dd日 HH:mm:ss"; //格式化显示时间NSDate *zt = [now addTimeInterval:-t];//时间差方法2formatter.dateFormat = @"yyyy年MM月dd日 HH:mm:ss"; //格式化显示时间

Foundation中类当然不止这些，列举的都是常用的。