【iOS开发】添加子控件方式(懒加载，GCC)

 1 //
 2 //  ViewController.m
 3 //  GCC
 4 //
 5 //  Created by admin on 15/10/7.
 6 //  Copyright © 2015年 admin. All rights reserved.
 7 //
 8 
 9 #import "ViewController.h"
10 
11 @interface ViewController ()
12 
13 @property (nonatomic, strong) UIButton* btn;
14 
15 @property (nonatomic, strong) UIButton* blueButton;
16 
17 @end
18 
19 @implementation ViewController
20 
21 - (void)viewDidLoad
22 {
23     [super viewDidLoad];
24 
25     UIButton* btn = [[UIButton alloc] initWithFrame:CGRectMake(100, 100, 100, 100)];
26     btn.backgroundColor = [UIColor redColor];
27 
28     [self.view addSubview:btn];
29     [self.view addSubview:self.btn];
30     [self.view addSubview:self.blueButton];
31 }
32 
33 ///  GCC
34 - (UIButton*)blueButton
35 {
36     if (!_blueButton) {
37 
38         _blueButton = ({
39             UIButton* btn = [[UIButton alloc] initWithFrame:({
40                                                   CGRect frame = CGRectMake(100, 400, 100, 100);
41                                                   frame;
42                                               })];
43             btn.backgroundColor = [UIColor blueColor];
44             btn;
45         });
46     }
47     return _blueButton;
48 }
49 
50 ///  懒加载的方式
51 - (UIButton*)btn
52 {
53     if (_btn == nil) {
54         _btn = [[UIButton alloc] initWithFrame:CGRectMake(100, 200, 100, 100)];
55         _btn.backgroundColor = [UIColor greenColor];
56     }
57 
58     return _btn;
59 }
60 
61 @end