关于awakeFromNib的学习

转自：http://blog.youkuaiyun.com/wangyangkobe/article/details/18996227

When a nib is loaded, the nib loader allocates and initializes all objects, then hooks up all of their outlets and actions. Because of the order in which this happens, you cannot access outlets in your initializer. You can try, but they will all be nil.

After all outlets and actions are connected, the nib loader sends awakeFromNib to every object in the nib. This is where you can access outlets to set up default values or do configuration in code. Example:

试译：当所有的“外引”和动作都连接完毕后，nib“加载器”就像nib文件上所有的对象（如button、view）发送awakeFromNib消息。

http://wiresareobsolete.com/wordpress/2010/03/awakefromnib/

[objc]  view plain copy

1. @implementation SecondView  
2.   
3. - (id)initWithFrame:(CGRect)frame  
4. {  
5.     self = [super initWithFrame:frame];  
6.     if (self) {  
7.         // Initialization code  
8.     }  
9.     return self;  
10. }  
11.   
12. - (void)awakeFromNib{  
13.     [super awakeFromNib];  
14.     NSLog(@"call %s", __FUNCTION__);  
15.     self.backgroundColor = [UIColor redColor];  
16. }  

一般在UIView的子类重载该方法。

[objc]  view plain copy

1. @implementation BlueButton  
2.   
3. - (id)initWithFrame:(CGRect)frame  
4. {  
5.     self = [super initWithFrame:frame];  
6.     if (self) {  
7.         // Initialization code  
8.     }  
9.     return self;  
10. }  
11. - (void)awakeFromNib{  
12.     [super awakeFromNib];  
13.     NSLog(@"call %s", __FUNCTION__);  
14.     self.backgroundColor = [UIColor blueColor];  
15.     [self setTitle:@"Blue Button" forState:UIControlStateNormal];  
16. }  
17. - (id)initWithCoder:(NSCoder *)aDecoder{  
18.     NSLog(@"call %@", @"initWithCoder");  
19.     if (self = [super initWithCoder:aDecoder]) {  
20.         self.titleLabel.text = @"initWithCoder";  
21.     }  
22.     return  self;  
23. }  
24. @end  

如果是从nib中加载BuleButton，方法 initWithCoder  会调用，并且先于  awakeFromNib  调用。