转自：http://blog.csdn.net/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.

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 plaincopy

@implementation SecondView  

  

- (id)initWithFrame:(CGRect)frame  

{  

    self = [super initWithFrame:frame];  

    if (self) {  

        // Initialization code  

    }  

    return self;  

}  

  

- (void)awakeFromNib{  

    [super awakeFromNib];  

    NSLog(@"call %s", __FUNCTION__);  

    self.backgroundColor = [UIColor redColor];  

}  

一般在UIView的子类重载该方法。

[objc] view plaincopy

@implementation BlueButton  

  

- (id)initWithFrame:(CGRect)frame  

{  

    self = [super initWithFrame:frame];  

    if (self) {  

        // Initialization code  

    }  

    return self;  

}  

- (void)awakeFromNib{  

    [super awakeFromNib];  

    NSLog(@"call %s", __FUNCTION__);  

    self.backgroundColor = [UIColor blueColor];  

    [self setTitle:@"Blue Button" forState:UIControlStateNormal];  

}  

- (id)initWithCoder:(NSCoder *)aDecoder{  

    NSLog(@"call %@", @"initWithCoder");  

    if (self = [super initWithCoder:aDecoder]) {  

        self.titleLabel.text = @"initWithCoder";  

    }  

    return  self;  

}  

@end  

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