最近开始实习，没多少时间更新了=_=

第九课：

　　1、上节课demo：Dropit完整实现

　　　　https://github.com/NSLogMeng/Stanford_iOS7_Study/commit/cfc24c2c4300185d972cf151872d313414a48d32

　　2、Autolayout

　　　　比较简单请参照课件截图https://github.com/NSLogMeng/Stanford_iOS7_Study/blob/master/Slides/Lecture%209%20Slides.pdf

　　　　课程实现方法为在storyboard中可视化实现，本文再介绍两种方法：

　　　　①NSLayoutConstraint

+(instancetype)constraintWithItem:(id)view1 
                                      attribute:(NSLayoutAttribute)attr1
                                     relatedBy:(NSLayoutRelation)
                             relation toItem:(id)view2 
                                      attribute:(NSLayoutAttribute)attr2 
                                     multiplier:(CGFloat)multiplier constant:(CGFloat)c;
//约束：item1.attribute =(>=,<=related) multiplier * item2.attribute + constant

//使用UIView添加约束
- (void)addConstraint:(NSLayoutConstraint *)constraint

　　　　②Visual Format Language（VFL）

　　　　　　官方文档很简单易懂

　　　　　　　　　　　　　　　　　　语法：

　　　　　　举例：

　　　　代码实现举例:

- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.
    UIButton *button1 = [[UIButton alloc] init];
    button1.backgroundColor = [self randomColor];
    [button1 setTitle:@"button1" forState:UIControlStateNormal];
    button1.translatesAutoresizingMaskIntoConstraints = NO;//手动创建的代码使用VFL必须更改此属性
    button1.layer.cornerRadius = 4.0f;
    [self.view addSubview:button1];
    
    [self.view addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"H:|-[button1]-|" options:0 metrics:nil views:NSDictionaryOfVariableBindings(button1)]];
    [self.view addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"V:|-20-[button1(width)]" options:0 metrics:@{@"width" : @30} views:NSDictionaryOfVariableBindings(button1)]];
    
    UIButton *button2 = [[UIButton alloc] init];
    button2.backgroundColor = [self randomColor];
    [button2 setTitle:@"button2" forState:UIControlStateNormal];
    button2.translatesAutoresizingMaskIntoConstraints = NO;//手动创建的代码使用VFL必须更改此属性
    button2.layer.cornerRadius = 4.0f;
    [self.view addSubview:button2];
    
    [self.view addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"H:|-[button2]-|" options:0 metrics:nil views:NSDictionaryOfVariableBindings(button2)]];
    [self.view addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"V:[button1]-44-[button2(30)]" options:0 metrics:nil views:NSDictionaryOfVariableBindings(button1,button2)]];
    
    UITabBar *tabBar = [[UITabBar alloc] init];
    tabBar.barTintColor = [UIColor colorWithRed:102/255.0f green:204/255.0f blue:255/255.0f alpha:1.0f];
    tabBar.translatesAutoresizingMaskIntoConstraints = NO;//手动创建的代码使用VFL必须更改此属性
    
    UITabBarItem *item1 = [[UITabBarItem alloc] init];
    [item1 setTitle:@"item1"];
    
    UITabBarItem *item2 = [[UITabBarItem alloc] init];
    [item2 setTitle:@"item2"];
    
    UITabBarItem *item3 = [[UITabBarItem alloc] init];
    [item3 setTitle:@"item3"];
    
    tabBar.items = @[item1,item2,item3];
    
    [self.view addSubview:tabBar];
    [self.view addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"H:|[tabBar]|" options:0 metrics:nil views:NSDictionaryOfVariableBindings(tabBar)]];
    [self.view addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"V:[tabBar(45)]|" options:0 metrics:nil views:NSDictionaryOfVariableBindings(tabBar)]];
    
    [button1 addTarget:self action:@selector(touchButton1) forControlEvents:UIControlEventTouchDown];
    
}

 　　　　　　　　注意：①代码创建的view要加 button1.translatesAutoresizingMaskIntoConstraints = NO;才能生效

　　　　　　　　　　　 ②metrics存储VFL中可变量的值（字典），可以参考button1的约束

　　　　　　　　　　　 ③views参数对应VFL中View的值（通过NSDictionaryOfVariableBindings(...)实现）

　　3、作业

　　　　还没做=_=,后面补。

课程视频地址：网易公开课：http://open.163.com/movie/2014/1/B/P/M9H7S9F1H_M9H80K2BP.html

　　　　　　　或者iTunes U搜索standford课程