[Objective-C 面试简要笔记]

Obj-C:

1.消息机制

[shape draw]  向该对象发送消息,该对象查找并运行此函数

差不多就是shape.draw();

2.中缀语法

[textThing setStringValue:@“Hello” color:[UIColor RedColor]];

3.代码重构:

减少重复代码,写成函数或者类

4.类的复合

汽车类由轮子类和车架类复合而成(伪多继承实现方式)

11.selector响应选择器

[car respondsToSelector:@selector(doxxx:)]

12.Category(类别)和类扩展

类别缺点:1.不能新加变量 2.重名会覆盖

Things为已有类

类别:(无法添加成员变量!)

@interface Things(Plus){

}

进行类扩展如下:(可以添加成员变量!)

@interface Things(){

}

13.协议和delegate委托(代理)

协议:

//协议定义

@protocol UpdateAlertDelegate <NSObject>

- (void)updateAlert;

@end

委托:协议基础上增加

@interface TimerControl : NSObject

//遵循协议的一个代理变量定义

@property (nonatomic, weak) id<UpdateAlertDelegate> delegate;

- (void) startTheTimer;

@end

14.block代码块:函数指针

创建:

int (^multiply_block)(int number)=^(int number){

return (number*number);

}

调用:

int result=multiply_block(5);

创建block变量:

typedef double (^MKSampleMultiply2BlockRef)(double c,double d);

MKSampleMultiply2BlockRef multiply2={ return c *d ; };

调用:

multiply2(4,5);

GCD多线程

15.调度队列:

1.连续队列

dispatch_queue_t my_serial_queue= dispatch_queue_create(“myQueue”,NULL);

2.并发队列

= dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY,0);

3.主队列

= dispatch_get_current_queue(void);

4.获取当前队列

= dispatch_get_current_queue();

16.程序调度

dispatch_block_t myBlock=^{ NSLog(@“A cute block!”) }

Block异步:dispatch_async(_serial_queue,^{  NSLog(@“TASK1 ”);   });

Block异步:dispatch_async(_serial_queue,myBlock);

异步函数:dispatch_async_f(_serial_queue,(_bridge void*)[NSNumber numberWithInt:3],(dispatch_function_t)myDispatchFunction);

队列暂停:

dispatch_suspend(_serial_queue);

队列重新开始

dispatch_resume(_serial_queue);

_bridge关键字

告诉ARC交给系统管理内存

17 操作队列 NSOperationQueue

1.创建代码块操作

NSBlockOperation *blockOperation=[NSBockOperation blockOperationWithBlock:^{

}];

2.[blockOperation addExecutionBlock:^{

}];

队列操作

1.当前队列

NSOperationQueue *currentQueue=[NSOperationQueue currentQueue];

2.主队列

[NSOperationQueue mainQueue];

3.队列添加代码块

[theQueue addOperation:blockOperation];

[theQueue addOperation:^{

nslog(@“aaa”);

}];

原文地址:https://www.cnblogs.com/rayshen/p/4547806.html