object c 基础语法#iOS#HeminWon

Objectve-C语法总结<2>

2015-12-04  本文已影响265人  天天想念

大纲

书接上篇，继续来说说这个古老而又现代的开发语言。在Objectve-C语法总结<1> 那篇中OC大部分的语法基本上已经总结完毕。本篇在上一篇的基础上对语法进行少量的补充，其次主要对OC中的常用类API的介绍。

26.Protocol-协议

26.1.protocol 概念

26.2.protocol 语法格式

@protocol 协议名称
// 方法声明列表
@end

@interface 类名 : 父类 <协议名称1, 协议名称2,…>
@end

@protocol SportProtocol <NSObject>
- (void)playFootball;
- (void)playBasketball;
@end

#import "SportProtocol.h" // 导入协议
@interface Studnet : NSObject<SportProtocol> // 遵守协议
@end

@implementation Student
// 实现协议方法
- (void)playBasketball
{
    NSLog(@"%s", __func__);
}
// 实现协议方法
- (void)playFootball
{
    NSLog(@"%s", __func__);
}
@end

26.3.protocol和继承区别

26.4.protocol 的使用注意

@protocol SportProtocol <NSObject>
{
    int _age; // 错误写法
}
- (void)playFootball;
- (void)playBasketball;
@end

@protocol SportProtocol <NSObject>

- (void)playFootball;
- (void)playBasketball;
@end

#import "SportProtocol.h"
@interface Student : NSObject <SportProtocol>
@end

@interface GoodStudent : Student
@end

@implementation GoodStudent
- (void)playFootball
{
    NSLog(@"%s", __func__);
}
- (void)playBasketball
{
    NSLog(@"%s", __func__);
}
@end

#import "SportProtocol.h"
#import "StudyProtocol.h"

@interface Student : NSObject <SportProtocol, StudyProtocol>

@end

@protocol A
-(void)methodA;
@end

@protocol B <A>
-(void)methodB;
@end

@interface Student : NSObject <B>
-(void)methodA; // 同时拥有A/B协议中的方法声明
-(void)methodB;
@end

26.5.基协议

@protocol SportProtocol <NSObject> // 基协议

- (void)playFootball;
- (void)playBasketball;
@end

26.6.@required和@optional关键字

@protocol SportProtocol <NSObject>

@required // 如果遵守协议的类不实现会报警告
- (void)playFootball;
@optional // 如果遵守协议的类不实现不会报警告
- (void)playBasketball;
@end

27.delegate-代理

27.1.代理设计模式

2.代理设计模式示例

#import <Foundation/Foundation.h>
@class Baby;
// 协议
@protocol BabyProtocol <NSObject>
- (void)feedWithBaby:(Baby *)baby;
- (void)hypnosisWithBaby:(Baby *)baby;
@end

给baby定义了一个协议BabyProtocol，里面有两个方法，分别是吃饭和睡觉。该协议继承了基协议<NSObject>

#import "BabyProtocol.h"
@interface Baby : NSObject
// 食量
@property (nonatomic, assign) int food;
// 睡意
@property (nonatomic, assign) int drowsiness;
// 饿
- (void)hungry;
// 睡意
- (void)sleepy;
@property (nonatomic, strong) id<BabyProtocol> nanny;
@end

@implementation Baby

- (void)hungry
{
    self.food -= 5;
    NSLog(@"婴儿饿了");
    // 通知保姆，respondsToSelector：判断保姆类中是否实现了feedWithBaby:方法，如果没有实现该方法就不会执行。
    if ([self.nanny respondsToSelector:@selector(feedWithBaby:)]) {
        [self.nanny feedWithBaby:self];
    }
}

- (void)sleepy
{
    self.drowsiness += 5;
    NSLog(@"婴儿困了");
    // 通知保姆
    if ([self.nanny respondsToSelector:@selector(hypnosisWithBaby:)]) {
        [self.nanny hypnosisWithBaby:self];
    }
}
@end

baby类的匿名分类中定义了，食量，睡意两个int类型属性，定义了id类型的nanny属性，协议属性使用id类型的原因是代表任何类都可以遵守BabyProtocol协议，扩展性强。同时定义了两个hungry，sleepy（睡觉）两个方法。

// 保姆
@interface Nanny : NSObject <BabyProtocol>
@end

@implementation Nanny

- (void)feedWithBaby:(Baby *)baby
{
    baby.food += 10;
    NSLog(@"给婴儿喂奶, 现在的食量是%i", baby.food);
}

- (void)hypnosisWithBaby:(Baby *)baby
{
    baby.drowsiness += 10;
    NSLog(@"哄婴儿睡觉, 现在的睡意是%i", baby.drowsiness);
}
@end

Nanny保姆类遵守了BabyProtocol协议，在baby发生饿了的行为时，会通知保姆，调用对应的方法。

int main(int argc, const char * argv[]) {
    // 1.创建婴儿
    Baby *b = [Baby new];
    // 2.创建保姆
    Nanny *n = [Nanny new];
    // 3.保姆作为婴儿的代理
    b.nanny = n;
    
    // 4.换保姆
//    Studnet *stu = [Studnet new];
    //保姆属性id类型的，任何类都可以作为代理
//    b.nanny = stu;
    
    //5.婴儿发飙，执行food方法，food方法会执行保姆类的对应方法。
    [b food];
    [b sleepy];
     
    return 0;
}

28.Foundation框架介绍

28.1.Foundation框架介绍

iOS提供了很多你可以在应用程序里调用的框架。要使用一个框架，需要将它添加到你的项目中，你的项目才可以使用它。许多应用程序都使用了如 Foundation、UIKit、和Core Graphics这些框架。根据你为应用程序选择的模版，相关的框架就已经被自动引入了。如果默认加入的框架不能满足你的应用程序的需求，你也可以加入需要的框架。
iOS应用程序基于Foundation和UIKit框架，在开发iOS程序时，主要使用框架就是Foundation和UIKit，因为它们包含了你需要的大部分东西。
每个框架对应IOS系统里的一层，每层建立在它下面层的上面。应该尽量使用上层的框架来代替下面的框架。更高层次的框架是对底层框架基于对象的抽象。
这两个框架在系统中的位置如下图：


NSString : 字符串
NSArray : 数组
NSDictionary : 字典
NSDate : 日期
NSData : 数据
NSNumber : 数字

29.NSString和NSMutableString

29.1.直接读写文件中的字符

// 用来保存错误信息
NSError *error = nil;

// 读取文件内容
NSString *str = [NSString stringWithContentsOfFile:@"/Users/XXX/Desktop/abc.txt" encoding:NSUTF8StringEncoding error:&error];

// 如果有错误信息
if (error) {
    NSLog(@"读取失败, 错误原因是:%@", [error localizedDescription]);
} else { // 如果没有错误信息
    NSLog(@"读取成功, 文件内容是:\n%@", str);
}

NSString *str = @"江哥";
BOOL flag = [str writeToFile:@"/Users/XXX/Desktop/abc.txt" atomically:YES encoding:NSUTF8StringEncoding error:nil];
if (flag == 1)
{
    NSLog(@"写入成功");
}

NSString *str1 = @"支付宝";
BOOL flag = [str1 writeToFile:@"/Users/XXX/Desktop/abc.txt" atomically:YES encoding:NSUTF8StringEncoding error:nil];

NSString *str2 = @"暖宝宝";
[str2 writeToFile:@"/Users/XXX/Desktop/abc.txt" atomically:YES encoding:NSUTF8StringEncoding error:nil];

NSString *str = [NSString stringWithContentsOfFile:@"/Users/XXX/Desktop/abc.txt" encoding:NSUTF8StringEncoding error:&error];
NSLog(@"str = %@", str);

输出结果:暖宝宝

29.2.NSString大小写处理

29.3.NSString比较

    NSString *str1 = @"gzs";
    NSString *str2 = [NSString stringWithFormat:@"gzs"];
    if ([str1 isEqualToString:str2]) {
        NSLog(@"字符串内容一样");
    }

    if (str1 == str2) {
        NSLog(@"字符串地址一样");
    }

    NSString *str1 = @"abc";
    NSString *str2 = @"abd";
    switch ([str1 compare:str2]) {
        case NSOrderedAscending:
            NSLog(@"后面一个字符串大于前面一个");
            break;
        case NSOrderedDescending:
            NSLog(@"后面一个字符串小于前面一个");
            break;
        case NSOrderedSame:
            NSLog(@"两个字符串一样");
            break;
    }
    输出结果: 后面一个字符串大于前面一个


    NSString *str1 = @"abc";
    NSString *str2 = @"ABC";
    switch ([str1 caseInsensitiveCompare:str2]) {
        case NSOrderedAscending:
            NSLog(@"后面一个字符串大于前面一个");
            break;
        case NSOrderedDescending:
            NSLog(@"后面一个字符串小于前面一个");
            break;
        case NSOrderedSame:
            NSLog(@"两个字符串一样");
            break;
    }
    输出结果:两个字符串一样

29.4.字符串搜索

29.5.NSRange基本概念

typedef struct _NSRange {
    NSUInteger location;
    NSUInteger length;
} NSRange;
// NSUInteger的定义
typedef unsigned int NSUInteger;

29.6.NSRange的创建

NSRange range;
range.location = 7;
range.length = 3;

NSRange range = {7, 3};
或者
NSRange range = {.location = 7,.length = 3};

NSRange range = NSMakeRange(7, 3);

29.7.字符串的截取

    NSString *str = @"<head>暖宝宝</head>";
    str = [str substringFromIndex:7];
    NSLog(@"str = %@", str);

    输出结果: 暖宝宝</head>

    NSString *str = @"<head>暖宝宝</head>";
    str = [str substringToIndex:10];
    NSLog(@"str = %@", str);

    输出结果: <head>暖宝宝

    NSString *str = @"<head>暖宝宝</head>";
    NSRange range;
    /*
    range.location = 6;
    range.length = 3;
    */
    range.location = [str rangeOfString:@">"].location + 1;
    range.length = [str rangeOfString:@"</"].location - range.location;
    NSString *res = [str substringWithRange:range];
    NSLog(@"res = %@", res);
输出结果: 暖宝宝

29.8.字符串的替换函数

    NSString *str = @"http:**baidu.com*img*ljn.gif";
    NSString *newStr = [str stringByReplacingOccurrencesOfString:@"*" withString:@"/"];
    NSLog(@"newStr = %@", newStr);

输出结果: http://www.baidu.com/img/ljn.gif

    NSString *str =  @"   http://baidu.com/img/ljn.gif   ";
    NSString *newStr = [str stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceCharacterSet]];
    NSLog(@"str =|%@|", str);
    NSLog(@"newStr =|%@|", newStr);

输出结果:
str =|   http://baidu.com/img/ljn.gif   |
newStr =|http://baidu.com/img/ljn.gif|


    NSString *str =  @"***http://baidu.com/img/ljn.gif***";
    NSString *newStr = [str stringByTrimmingCharactersInSet:[NSCharacterSet characterSetWithCharactersInString:@"*"]];

    NSLog(@"str =|%@|", str);
    NSLog(@"newStr =|%@|", newStr);

输出结果:
str =|***http://baidu.com/img/ljn.gif***|
newStr =|http://baidu.com/img/ljn.gif|

29.9.NSString与路径

     // 其实就是判断是否以/开头
//    NSString *str = @"/Users/My-Lee/Desktop/bai.txt";
    NSString *str = @"Users/My-Lee/Desktop/bai.txt";
    if ([str isAbsolutePath]) {
        NSLog(@"是绝对路径");
    }else
    {
        NSLog(@"不是绝对路径");
    }

    // 截取最后一个/后面的内容
    NSString *str = @"/Users/My-Lee/Desktop/bai.txt";
    NSString *component = [str lastPathComponent];
    NSLog(@"component = %@", component);

    // 其实就是上次最后一个/和之后的内容
    NSString *str = @"/Users/My-Lee/Desktop/bai.txt";
    NSString *newStr = [str stringByDeletingLastPathComponent];
    NSLog(@"newStr = %@", newStr);

// 其实就是在最后面加上/和要拼接得内容
    // 注意会判断后面有没有/有就不添加了, 没有就添加, 并且如果有多个会替换为1个
//    NSString *str = @"/Users/My-Lee/Desktop";
    NSString *str = @"/Users/My-Lee/Desktop/";
    NSString *newStr = [str stringByAppendingPathComponent:@"bai"];
    NSLog(@"newStr = %@", newStr);

29.10.NSString与文件拓展名

    // 其实就是从最后面开始截取.之后的内容
//    NSString *str = @"abc.txt";
    NSString *str = @"abc.txt";
    NSString *extension = [str pathExtension];
    NSLog(@"extension = %@", extension);

    // 其实就是上次从最后面开始.之后的内容
//    NSString *str = @"abc.txt";
    NSString *str = @"abc.txt";
    NSString *newStr = [str stringByDeletingPathExtension];
    NSLog(@"newStr = %@", newStr);

// 其实就是在最后面拼接上.和指定的内容
    NSString *str = @"abc";
    NSString *newStr = [str stringByAppendingPathExtension:@"gif"];
    NSLog(@"newStr = %@", newStr);

29.11.字符串和其他数据类型转换

    NSString *str1 = @"110";
    NSString *str2 = @"10";
    int res = str1.intValue + str2.intValue;
    NSLog(@"res = %i", res);

    NSString *str1 = @"110";
    NSString *str2 = @"10.1";
    double res = str1.doubleValue + str2.doubleValue;
    NSLog(@"res = %f", res);

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

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

29.12.NSMutableString 基本概念

29.12.2.字符串中的可变和不可变
    // 改变了指针的指向, 并没有修改字符串
    NSString *str = @"abc";
    str = @"lmj";

    // 生成了一个新的字符串, 并没有修改字符串
    NSString *newStr = [str substringFromIndex:1];
    NSLog(@"str = %@", str);
    NSLog(@"newStr = %@", newStr);

    NSMutableString *strM = [NSMutableString string];
    NSLog(@"strM = %@", strM);
     // 修改原有字符串, 没有生成新的字符串
    [strM appendString:@"abc"];
    NSLog(@"strM = %@", strM);
    [strM appendString:@" v587"];
    NSLog(@"strM = %@", strM);
29.12.3.NSMutableString常用方法
    NSMutableString *strM = [NSMutableString stringWithString:@"http://www.baidu.com"];
     // 一般情况下利用rangeOfString和deleteCharactersInRange配合删除指定内容
     NSRange range = [strM rangeOfString:@"http://"];
     [strM deleteCharactersInRange:range];
     NSLog(@"strM = %@", strM);

    NSMutableString *strM = [NSMutableString stringWithString:@"www.520it.com"];
    [strM insertString:@"http://" atIndex:0];
    NSLog(@"strM = %@", strM);


    NSMutableString *strM = [NSMutableString stringWithString:@"http://www.baidu.com/abc.png"];
    NSRange range = [strM rangeOfString:@"gzs"];
    [strM replaceOccurrencesOfString:@"gzs" withString:@"jjj" options:0 range:range];
    NSLog(@"strM = %@", strM);
29.12.4.字符串使用注意事项
NSMutalbeString *s1 = @”abc”;
// 会报错
[strM insertString:@"my name is " atIndex:0];

30.NSArray和NSMutableArray

30.1.NSArray介绍

30.1.1.NSArray的创建方式

30.1.2.NSArray 的使用注意事项
    NSArray *arr = [NSArray arrayWithObjects:@"aaa", nil ,@"bbb",@"ccc", nil];
    NSLog(@"%@", arr);
    
    输出结果:
    (
        aaa
    )
30.1.3.NSArray的常用方法
30.1.4.NSArray的简写形式
[NSArray arrayWithObjects:@"Jack", @"Rose", @"Jim", nil];

+ 现在

@[@"Jack", @"Rose", @"Jim"];

[array objectAtIndex:0];

+ 现在

array[0];
30.1.5.NSArray遍历
    NSArray *arr = @[p1, p2, p3, p4, p5];
    for (int i = 0; i < arr.count; ++i) {
        Person *p = arr[i];
        [p say];
    }

    NSArray *arr = @[p1, p2, p3, p4, p5];
   for (Person *p in arr) {
        [p say];
    }

    [arr enumerateObjectsUsingBlock:^(id obj, NSUInteger idx, BOOL *stop) {
        NSLog(@"obj = %@, idx = %lu", obj, idx);
        Person *p = obj;
        [p say];
    }];
30.1.6.NSArray给所有元素发消息
    // 让数组中所有对象执行这个方法
    // 注意: 如果数组中的对象没有这个方法会报错
//    [arr makeObjectsPerformSelector:@selector(say)];
    [arr makeObjectsPerformSelector:@selector(eat:) withObject:@"bread"];
30.1.7.NSArray排序
NSArray *arr = @[@(1), @(9), @(5), @(2)];
NSArray *newArr = [arr sortedArrayUsingSelector:@selector(compare:)];

    NSArray *arr = @[p1, p2, p3, p4, p5];
    //    默认按照升序排序
    NSArray *newArr = [arr sortedArrayWithOptions:NSSortConcurrent usingComparator:^NSComparisonResult(Person *obj1, Person *obj2) {
        return obj1.age > obj2.age;
    }];
    NSLog(@"%@", newArr);
30.1.8.NSArray文件读写
    NSArray *arr = @[@"aaa", @"bbb", @"ccc", @"ddd"];
    BOOL flag = [arr writeToFile:@"/Users/XXX/Desktop/persons.plist" atomically:YES];
    NSLog(@"%i", flag);

    NSArray *newArr = [NSArray arrayWithContentsOfFile:@"/Users/XXX/Desktop/persons.plist"];
    NSLog(@"%@", newArr);

30.2.NSMutableArray介绍

30.2.1.NSMutableArray基本用法
NSMutableArray *arr = [NSMutableArray array];

NSMutableArray *arr2 = [[NSMutableArray alloc] initWithCapacity:5];

NSMutableArray *arr3 = [NSMutableArray arrayWithObjects:@"1",@"2", nil];

NSMutableArray *arr4 = [[NSMutableArray alloc] initWithObjects:@"1",@"2", nil];
30.2.2.NSMutableArray 错误用法
NSMutableArray *array = @[@"gzs", @"zzs", @"jjj"];
// 报错, 本质还是不可变数组
[array addObject:@“Peter”];

31. NSDictionary和NSMutableDictionary

31.1.NSDictionar基本概念

31.2.NSDictionary的创建

NSDictionary *dict = [NSDictionary dictionaryWithObjectsAndKeys:@"gzs", @"name", @"12345678", @"phone", @"gg", @"address", nil];

+ 现在

NSDictionary *dict = @{@"name":@"gzs", @"phone":@"12345678", @"address":@"gg"};

[dict objectForKey:@"name”];

+ 现在

dict[@"name”];

31.3.NSDictionary的遍历

    NSDictionary *dict = @{@"name":@"gzs", @"phone":@"12345678", @"address":@"gg"};
    for (NSString *key in dict) {
        NSLog(@"key = %@, value = %@", key, dict[key]);
    }

   [dict enumerateKeysAndObjectsUsingBlock:^(NSString *key,     NSString *obj, BOOL *stop) {
        NSLog(@"key = %@, value = %@", key, obj);
    }];

31.4.NSDictionary文件操作

    NSDictionary *dict = @{@"name":@"gzs", @"phone":@"12345678", @"address":@"gg"};
    BOOL flag = [dict writeToFile:@"/Users/XXX/Desktop/dict.plist" atomically:YES];
    NSLog(@"flag = %i", flag);

NSDictionary *newDict = [NSDictionary dictionaryWithContentsOfFile:@"/Users/XXX/Desktop/dict.plist"];
    NSLog(@"newDict = %@", newDict);

31.5.NSMutableDictionary 基本概念

31.6.NSMutableDictionary的常见操作

31.7.NSMutableDictionary的简写

[dict setObject:@"Jack" forKey:@"name”];

+ 现在

dict[@"name"] = @"Jack";

31.8.NSDictionary和NSArray对比

@[@"Jack", @"Rose"] (返回是不可变数组)

+ 访问

id d = array[1];

+ 赋值

array[1] = @"jack";

@{ @"name" : @"Jack", @"phone" : @"10086" } (返回是不可变字典)

+ 访问

id d = dict[@"name"];

+ 赋值

dict[@"name"] = @"jack";

32.copy

32.1.copy基本概念

32.2.Copy的使用

@protocol NSCopying
\- (id)copyWithZone:(NSZone *)zone;
@end


@protocol NSMutableCopying
- (id)mutableCopyWithZone:(NSZone *)zone;
@end

32.3.深复制和浅复制

    NSString *srcStr = @"gzs";
    NSString *copyStr = [srcStr copy];
    NSLog(@"src = %p, copy = %p", srcStr, copyStr);// %p代表打印内存地址

    输出结果：
    [869:162266] src = 0x1084c2140, copy = 0x1084c2140

    NSString *srcStr = @"gzs";
    NSMutableString *copyStr = [srcStr mutableCopy];
    NSLog(@"src = %p, copy = %p", srcStr, copyStr);
    NSLog(@"src = %@, copy = %@", srcStr, copyStr);
    [copyStr appendString:@" cool"];
    NSLog(@"src = %@, copy = %@", srcStr, copyStr);

    输出结果：
    [889:195883] src = 0x102a26140, copy = 0x7fec11f96790
    [889:195883] src = gzs, copy = gzs
    [889:195883] src = gzs, copy = gzs cool
    输出结果可以看出，mutableCopy出来的对象是一个新的对象，分配了新的内存地址。
    新的对象也可以进行字符串的拼接是一个可变的对象。

    NSMutableString *srcStr = [NSMutableString stringWithFormat:@"gzs"];
    NSString *copyStr = [srcStr copy];
    [srcStr appendString:@" cool"];
    NSLog(@"src = %p, copy = %p", srcStr, copyStr);
    NSLog(@"src = %@, copy = %@", srcStr, copyStr);

    输出结果：
    [913:205502] src = 0x7f8afadb0da0, copy = 0xa00000000737a673
    [913:205502] src = gzs cool, copy = gzs

    NSMutableString *srcStr = [NSMutableString stringWithFormat:@"gzs"];
    NSMutableString *copyStr = [srcStr mutableCopy];
    [srcStr appendString:@" cool"];
    [copyStr appendString:@"so cool"];
    NSLog(@"src = %p, copy = %p", srcStr, copyStr);
    NSLog(@"src = %@, copy = %@", srcStr, copyStr);

    输出结果：
    [946:208239] src = 0x7fe9a2e1b710, copy = 0x7fe9a2e1b750
    [946:208239] src = gzs cool, copy = gzs so cool

32.4.@property中的copy的作用

    @interface Person : NSObject
    @property (nonatomic, retain) NSString *name;
    @end

//在另外一个文件使用Person对象的时候，对象的name可以被修改，
//如果是copy就是对象的name复制了一份，name的值就不会被修改。

    NSMutableString *str = [NSMutableString stringWithFormat:@"gzs"];

    Person *p = [[Person alloc] init];
    p.name = str;
    // person中的属性会被修改
    [str appendString:@" cool"];
    NSLog(@"name = %@", p.name);

    Person *p = [[Person alloc] init];
    p.name = @"gzs";
    Dog *d = [[Dog alloc] init];
    d.age = 10;
    NSLog(@"retainCount = %lu", [d retainCount]); // 1
    p.pBlock = ^{
        // 报错, 调用之前就销毁了
        NSLog(@"age = %d", d.age);
    };
    [d release]; // 0
    p.pBlock();
    [p release];

+ 用copy情况

    Person *p = [[Person alloc] init];
    p.name = @"gzs";
    Dog *d = [[Dog alloc] init];
    d.age = 10;
    NSLog(@"retainCount = %lu", [d retainCount]); // 1
    p.pBlock = ^{
        // 会对使用到的外界对象进行一次retain
        NSLog(@"age = %d", d.age);
        NSLog(@"retainCount = %lu", [d retainCount]); // 1
    };
    [d release]; // 1
    p.pBlock();
    [p release];

32.5.@property内存管理策略选择

33.常见的结构体

33.1.NSPoint和CGPoint

typedef CGPoint NSPoint;

CGPoint的定义
struct CGPoint {
  CGFloat x;
  CGFloat y;
};
typedef struct CGPoint CGPoint;
typedef double CGFloat;

33.2.NSSize和CGSize

typedef CGSize NSSize;

CGSize的定义
struct CGSize {
  CGFloat width;
  CGFloat height;
};
typedef struct CGSize CGSize;

33.3.NSRect和CGRect

typedef CGRect NSRect;

CGRect的定义
struct CGRect {
  CGPoint origin;
  CGSize size;
};
typedef struct CGRect CGRect;

34.NSFileManager介绍

34.1NSFileManager定义

[NSFileManager defaultManager]

34.2.NSFileManager用法

    NSFileManager *manager = [NSFileManager defaultManager];
    // 可以判断文件
    BOOL flag = [manager fileExistsAtPath:@"/Users/XXX/Desktop/gzs.txt"];
    NSLog(@"flag = %i", flag);
    // 可以判断文件夹
    flag = [manager fileExistsAtPath:@"/Users/XXX/Desktop/未命名文件夹"];
    NSLog(@"flag = %i", flag);

    NSFileManager *manager = [NSFileManager defaultManager];
    BOOL directory = NO;
    BOOL flag = [manager fileExistsAtPath:@"/Users/XXX/Desktop/未命名文件夹" isDirectory:&directory];
    NSLog(@"flag = %i, directory = %i", flag, directory);

34.3.NSFileManager的文件访问

    NSFileManager *manager = [NSFileManager defaultManager];
    NSDictionary *dict = [manager attributesOfItemAtPath:@"/Users/XXX/Desktop/gzs.txt" error:nil];
    NSLog(@"dit = %@", dict);

    NSFileManager *manager = [NSFileManager defaultManager];
    NSArray *paths = [manager contentsOfDirectoryAtPath:@"/Users/XXX/Desktop/" error:nil];
    NSLog(@"paths = %@", paths);

    NSFileManager *manager = [NSFileManager defaultManager];
    NSArray *paths = [manager subpathsAtPath:@"/Users/XXX/Desktop/"];
    NSLog(@"paths = %@", paths);

34.4.NSFileManager的文件操作

    NSFileManager *manager = [NSFileManager defaultManager];
    BOOL flag = [manager createDirectoryAtPath:@"/Users/XXX/Desktop/test" withIntermediateDirectories:YES attributes:nil error:nil];
    NSLog(@"flag = %i", flag);

    NSString *str = @"gzs";
    NSData  *data = [str dataUsingEncoding:NSUTF8StringEncoding];
    NSFileManager *manager = [NSFileManager defaultManager];
    BOOL flag = [manager createFileAtPath:@"/Users/XXX/Desktop/abc.txt" contents:data attributes:nil];
    NSLog(@"flag = %i", flag);

35.其他

nil，NULL，Nil和NSNull区别

35.1.nil
NSString *someString = nil;
NSURL *someURL = nil;
id someObject = nil;
if (anotherObject == nil) // do something
35.1.2.NULL
int *pointerToInt = NULL;
char *pointerToChar = NULL;
struct TreeNode *rootNode = NULL;
35.1.3.Nil
Class someClass = Nil;
Class anotherClass = [NSString class];
35.1.4.NSNull
上一篇 下一篇

猜你喜欢

热点阅读