(9/18)重學Standford_iOS7開發_動畫、自動布局_課程筆記

2019-11-14 18:39:41

字體：大中小

來源：轉載

供稿：網友

最近開始實習，沒多少時間更新了=_=

第九課：

　　1、上節課demo：Dropit完整實現

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

　　2、Autolayout

　　　　比較簡單請參照課件截圖https://github.com/NSLogMeng/Stanford_iOS7_Study/blob/master/Slides/Lecture%209%20Slides.pdf

　　　　課程實現方法為在storyboard中可視化實現，本文再介紹兩種方法：

　　　　①NSLayoutConstraint

+(instancetype)constraintWithItem:(id)view1                                       attribute:(NSLayoutAttribute)attr1                                     relatedBy:(NSLayoutRelation)                             relation toItem:(id)view2                                       attribute:(NSLayoutAttribute)attr2                                      multiplier:(CGFloat)multiplier constant:(CGFloat)c;//約束：item1.attribute =(>=,<=related) multiplier * item2.attribute + constant//使用UIView添加約束- (void)addConstraint:(NSLayoutConstraint *)constraint

　　　　②Visual Format Language（VFL）

　　　　　　官方文檔很簡單易懂

　　　　　　　　　　　　　　　　　　語法：

含義	語法	含義	語法
水平方向	H:	關系	>=,<=,==
垂直方向	V:	空間，間隙	-
Views	[view]	優先級	@value
superView	\|

　　　　　　舉例：

　　　　代碼實現舉例:

- (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;//手動創建的代碼使用VFL必須更改此屬性    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;//手動創建的代碼使用VFL必須更改此屬性    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;//手動創建的代碼使用VFL必須更改此屬性        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];    }