一、Block的基本概念
Block是程序的代码块，这个代码块可以在需要的时候执行。IOS开发中，block到处可见，所以学好很重要
二、Block的基本用法
|
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
|
//// main.m// Block//// Created by apple on 14-3-26.// Copyright (c) 2014年 apple. All rights reserved.// #import <Foundation/Foundation.h> //最基本的用法void test(){ int (^Sum)(int, int) = ^(int a, int b) { return a + b; }; NSLog(@"%i", Sum(10, 11));} //也是基本用法，另外Block代码段中可以使用外边的mul变量，但是不可以改变他的值，如果下改变他的值，可以使用__block来定义mulvoid test1(){ int mul = 7; int (^myBlock)(int) = ^(int num) { return mul * num; }; int c = myBlock(7); NSLog(@"%i", c);} //改变外边变量的值void test2(){ __block int mul = 7; int (^myBlock)(int) = ^(int num) { mul = 10; NSLog(@"mul is %i", mul); return mul * num; }; int c = myBlock(7); NSLog(@"%i", c);} //给block起一个别名，之后我们就可以任意命名的来使用blockvoid test3(){ typedef int (^MySum)(int, int); MySum sum = ^(int a, int b) { return a + b; }; int c = sum(20, 39); NSLog(@"%i", c); } int main(int argc, const char * argv[]){ @autoreleasepool { test(); } return 0;} |
OK，都有注释。在main函数中调用即可测试
三、Block来实现委托模式
|
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
|
//// Button.h// Block_Button//// Created by apple on 14-3-26.// Copyright (c) 2014年 apple. All rights reserved.// #import <Foundation/Foundation.h>@class Button; //给block给一个别名ButtonBlocktypedef void (^ButtonBlock)(Button *); @interface Button : NSObject //定义一个block的成员变量，暂时写成assign@property (nonatomic, assign) ButtonBlock block; -(void)click; @end |
|
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
|
//// Button.m// Block_Button//// Created by apple on 14-3-26.// Copyright (c) 2014年 apple. All rights reserved.// #import "Button.h" @implementation Button //模拟点击-(void)click{ //回调函数，回调block _block(self);} @end |
|
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
|
//// main.m// Block_Button//// Created by apple on 14-3-26.// Copyright (c) 2014年 apple. All rights reserved.// #import <Foundation/Foundation.h>#import "Button.h" int main(int argc, const char * argv[]){ @autoreleasepool { Button *btn = [[[Button alloc] init] autorelease]; //回调的函数 btn.block = ^(Button *btn) { NSLog(@"%@被点击", btn); }; [btn click]; } return 0;} |
微信扫一扫，打赏作者吧～转载请注明：苏demo的别样人生 » OC之Block的用法和实现委托
