Objective-C 入门篇(推荐)

目录

• 前言
• 基本数据类型
  • 其他数据类型
    • id类型
    • BOOL类型
    • nil和Nil
    • NSString（不可变字符串）
    • NSMutableString（可变字符串）
    • NSInteger、NSUInteger和NSNumber
• 集合
  • 1. NSArray（不可变）
  • 2. NSMutableArray（可变的）
• 字典
  • NSDictionary
  • NSMutableDictionary
  • NSSet && NSMutableSet
• 消息传递
• 类
  • 访问修饰符
  • 属性
• 方法
  • 构造方法
  • 创建类对象
  • self
  • 继承
  • 多态
  • Runtime
• Category（类别）
• Extension（拓展）
• 异常处理
• 协议
• block
• 内存管理
• 参考资料

int main(int argc, char *argv[])
{
    @autoreleasepool //创建自动内存释放池
    {
    	//打印输出
        NSLog(@"hello world ios!");
        return 0;
    }
}

//字符串
NSString *str1 = @"ABC3456789";
//拼接成新的字符串
 NSString *str2 = [str1 stringByAppendingString:@"wwww"];
NSLog(@"str = %@", str2);
//遍历
for (int i = 0; i < [str2 length]; i++) {
    char temp = [str2 characterAtIndex:i];
    NSLog(@"字符串第 %d 位输出 %c", i, temp);
}
//比较
// sEqualToString方法 ：比较字符串是否完全相等，大小写不一样也无法完全匹配。
//hasPrefixe方法：逐一匹配字符串头部。haSuffix方法：匹配字符串的尾部
if ([str2 isEqualToString:str1]) {
    NSLog(@"相等");
}
if ([str2 hasPrefix:@"www"]) {
    NSLog(@"有该头部");
}
if ([str2 hasSuffix:@"www"]) {
    NSLog(@"有该尾部");
}
if ([str2 compare:str options:NSCaseInsensitiveSearch | NSNumericSearch] == NSOrderedSame) {
}
NSLog(@"比较结果：%d", [str2 caseInsensitiveCompare:str1]);
//大小写转换
NSLog(@"str3转大写：%@",[str2 uppercaseString]);
NSLog(@"str3转小写：%@",[str2 lowercaseString]);
NSLog(@"str3首字母转大写：%@",[str2 capitalizedString]);
//字符串截取
NSRange rang = NSMakeRange(2, 2);
NSLog(@"str3截取：%@",[str2 substringWithRange:rang]);
//搜索
NSRange rang1 = [str2 rangeOfString:@"www"];
NSLog(@"location: %d,length: %d",rang1.location,rang1.length);
//替换
//全部替换
NSString *str3 = [str2 stringByReplacingOccurrencesOfString:@" " withString:@"@"];
NSLog(@"替换后字符串为%@", str3);
//局部替换
NSString *str4 = [str2 stringByReplacingCharactersInRange:rang withString:@"met"];
NSLog(@"替换后字符串为%@", str4);

		//创建对象并初始化
		NSMutableString *mStr = [[NSMutableString alloc]init];
        //appendstring：向字符串尾部添加一个字符串。
        //appendFormat：向字符串尾部添加多个类型的字符串，可以添加任意数量与类型的字符串。
        [mStr appendString:@"hello world!"];
        NSLog(@"字符串创建%@", mStr);
        [mStr deleteCharactersInRange:[mStr rangeOfString:@"hello"]];
        //删除
        NSLog(@"字符串删除%@", mStr);
        //插入
        [mStr insertString:@"love you" atIndex: mStr.length];
        NSLog(@"字符串插入%@", mStr);

//包装
NSNumber *intNumber = [[NSNumber alloc]initWithInt:43];
//或者字面量方式
NSNumber *intNumber1 = @43;
//还原基本数据类型，解包
NSLog(@"%d",[intNumber intValue]);

//字面量创建方式
    NSArray *arr2 = @[@"aaa",@"bbbbb"];
//工厂方法创建
    NSArray *array = [[NSArray alloc] initWithObjects:@"1", @"2", nil];
    //取最后一个元素
    [array lastObject];
//    取第一个元素
    [array firstObject];
//    数组是否包含某个元素
    [array containsObject:@"1"];
//    数组的大小
    int count = (int) array.count;
//    第一种方式遍历
    for (int i = 0; i < count; i++) {
        NSString *_str = [array objectAtIndex:i];
    }

// 字面量创建二维数组并访问
NSArray *arr2 = @[@[@11, @12, @13], @[@21, @22, @23], @[@31, @32, @33]];
// 字面量访问方式(推荐)
NSLog(@"arr2[2][2]:%@", arr2[2][2]);
// 数组对象函数访问
NSLog(@"arr2[2][2]:%@", [[arr2 objectAtIndex:2] objectAtIndex:2]);

		//创建，当然还有其他方式
        NSMutableArray *mutableArr = [NSMutableArray arrayWithObjects:@"one",@"two",@"three", nil];
        //添加
        [mutableArr addObject:@"hello"];
        //替换
        [mutableArr replaceObjectAtIndex:2 withObject:@"tihuan"];
        //删除
        [mutableArr removeObjectAtIndex:1];
        //插入
        [mutableArr insertObject:@"ios" atIndex:1];

   		// 初始化作为列的数组，看做4列
NSMutableArray *columnArray = [[NSMutableArray alloc]initWithCapacity:4];

// 初始化2个一维数组，每个一维数组有4个元素，看做1行4列，2行加起来就是2行4列
NSMutableArray *rowArray1 = [[NSMutableArray alloc]initWithCapacity:4];
NSMutableArray *rowArray2 = [[NSMutableArray alloc]initWithCapacity:4];

// 每个行依次增加数组元素
// 第一行
[rowArray1 addObject:@"11"];
[rowArray1 addObject:@"12"];
[rowArray1 addObject:@"13"];
[rowArray1 addObject:@"14"];

// 第二行
[rowArray2 addObject:@"21"];
[rowArray2 addObject:@"22"];
[rowArray2 addObject:@"23"];
[rowArray2 addObject:@"24"];

// 分别打印数组
NSLog(@"myRowArray1: %@", rowArray1);
NSLog(@"myRowArray2: %@", rowArray2);
NSLog(@"myColumnArray: %@", columnArray);

	//标准创建
    NSDictionary *dict = [NSDictionary dictionaryWithObjectsAndKeys:@"cat",@"name1",@"dog",@"name2", nil];
    //字面量创建
    NSDictionary *dict1 = @{@"name1":@"cat",@"name2":@"dog"};
	//第一种遍历
    for (NSString *key in [dict1 allKeys]) {
        NSLog(@"key: %@,value: %@", key, dict1[key]);
    }
    //第二种遍历方式，通过遍历器
    NSEnumerator *rator = [dict keyEnumerator];
    NSString *temp;
    while (temp = [rator nextObject]) {
        NSLog(@"%@", temp);
    }
    //获取元素
	dict1[@"name"];
	[dict1 objectForKey:@"name"];
	//集合元素的个数
	NSInteger count = dict1.count;
	//沙盒文件存储和读取Plist
	[dict5 writeToFile:@"路径" atomically:YES];
	NSDictionary *dict7 = [NSDictionary dictionaryWithContentsOfFile:@"路径"];

//创建
NSMutableDictionary *dict = [NSMutableDictionary dictionary];
//添加
[dict setObject:@"dog" forKey:@"name"];
[dict setValue:@"18" forKey:@"age"];
//会将传入字典中所有的键值对取出来添加到dict中
[dict setValuesForKeysWithDictionary:@{@"name1":@"dog"}];
//取元素
[dict objectForKey:@"name"];
dict[@"name"];
//删除
[dict removeAllObjects];
[dict removeObjectForKey:@"name"];
[dict removeObjectsForKeys:@[@"name", @"age"]];
//更新，如果利用setObject方法给已经存在的key赋值，新值会覆盖旧值
[dict setObject:@"20" forKey:@"age"];
dict[@"age"] = @"30";

NSString *sourceString = [NSString stringWithFormat:@"hello ios"];
//不产生新的内存空间
NSString *copyStr = [sourceString copy];
//产生新的内存空间
NSMutableString *mutableStr = [sourceString mutableCopy];
NSLog(@"sourceString : %@   %p",sourceString,sourceString);
NSLog(@"copyStr : %@    %p",copyStr,copyStr);
NSLog(@"mutableStr : %@     %p",mutableStr,mutableStr);

//代码块   
NSMutableString *string = [NSMutableString stringWithString:@"origin"];//copy
NSString *stringCopy = [string copy];
NSLog(@"string address is: %p",string);
NSLog(@"stringCopy address is: %p",stringCopy);

NSMutableString *string = [NSMutableString stringWithString:@"origin"];
//NSString *stringCopy = [string copy];
NSString *stringCopy = string;
[string appendString:@"change"];
NSLog(@"string address is: %p",string);
NSLog(@"stringCopy address is: %p",stringCopy);

//无参数
- (void)print；
//有参数
- (void)print:(int)a andB:(int)b;

/**
 重写初始化方法
 **/
- (instancetype)init
{
    self = [super init];
    if (self) {
        _peopleName = @"hello ios";
    }
    return self;
}

/**
 自定义初始化方法
 **/
- (instancetype)initWithNameAndAge:(NSString *)name andAge:(int)age
{
    self = [super init];
    if (self) {
        _peopleName = name;
        _peopleAge = age;
    }
    return self;
}

People *p1 = [[People alloc] init];
//调用自定义的构造方法
People *p3 = [[People alloc] initWithNameAndAge:@"mingzi" andAge:12];
//调用方法
[p3 print];

//Computer.h文件
#import <Foundation/Foundation.h>
@interface Computer : NSObject
@property(nonatomic,strong)NSString *name;
-(void)calculate;
@end

//  Computer.m
#import "Computer.h"
@implementation Computer
@synthesize name;
-(void) calculate{
    NSLog(@"i can calculate");
}
@end

//  MacBook.h
#import "Computer.h"
@interface MacBook : Computer
@end

//  MacBook.m
#import "MacBook.h"
@implementation MacBook
@end

//main.m
int main(int argc, char *argv[])
{
    @autoreleasepool
    {
        MacBook *macBook = [[MacBook alloc] init];
        macBook.name = @"mac";
        [macBook calculate];
    }
}

#import <UIKit/UIKit.h>
#import "AppDelegate.h"
#import <objc/runtime.h>
#import <objc/message.h>
void sayHi(id self, IMP _cmd, id some)
{
    //self指的是调用该方法传过来的类
    NSLog(@"%@说:%@，我%@岁", [self valueForKey:@"name"], some, object_getIvar(self, class_getInstanceVariable([self class], "_age")));
}

int main(int argc, char *argv[])
{
    @autoreleasepool
    {
        //该方法动态创建一个类，arg1:继承自哪个类 arg2:新建类的名称 arg3:extraBytes
        Class Person = objc_allocateClassPair([NSObject class], "Person", 0);
        //添加两个实例变量name和age，arg2:变量名称，arg3:内存地址大小，arg5:变量类型
        class_addIvar(Person, "_name", sizeof(NSString *), log2(sizeof(NSString *)), @encode(NSString *));
        class_addIvar(Person, "_age", sizeof(int), sizeof(int), @encode(int));
        //注册方法名
        SEL s = sel_registerName("say:");
        //arg3:IMP是“implementation”的缩写，这个函数指针决定了最终执行哪段代码
        //arg4:方法的参数及返回值
        class_addMethod(Person, s, (IMP)sayHi, "v@:@");
        //通过该类创建一个实体的对象
        id peopleInstance = [[Person alloc]init];
        //给对象的 name 实例变量赋值，下面是第二种赋值方式
        [peopleInstance setValue:@"XQM" forKey:@"name"];
        //Ivar nameIvar = class_getInstanceVariable(Person, "_name");
        //object_setIvar(peopleInstance, nameIvar, @"XQM");
        //获取实例变量
        Ivar ageIvar = class_getInstanceVariable(Person, "_age");
        //为变量赋值
        object_setIvar(peopleInstance, ageIvar, @21);
        //调用sayHi方法，arg2:注册指定的方法；arg3:带上有一个字符串的参数
        ((void(*)(id, SEL, id))objc_msgSend)(peopleInstance, s, @"大家好");
        //调用完成,将对象置为空
        peopleInstance = nil;
        //通过 objc 销毁类，销毁的是一个类不是对象
        objc_disposeClassPair(Person);
    }
}

@interface UIImageView (ImageViewLoader) <AysncImageDownloaderDelegate>
- (void)setOnlineImage:(NSString *)url placeholderImage:(UIImage *)image withRow:(NSNumber *)row;
@end

@implementation UIImageView (ImageViewLoader)

- (void)setOnlineImage:(NSString *)url placeholderImage:(UIImage *)image withRow:(NSNumber *)row;
{
    self.image = image;
    AsyncImageDownLoader *downloader = [AsyncImageDownLoader sharedImageDownloader];
    [downloader startWithUrl:url delegate:self withRow:row];
}
@end

@interface ViewController ()
@property (nonatomic, copy) block b;
@end

@implementation ViewController
@end

@protocol ClickDelegate
- (void)click;
- (void)unclick;
@end