ios开发autolayout之VFL语言使用总结

来源：互联网发布：最新电视直播软件编辑：程序博客网时间：2024/06/05 02:42

1.about VFL language

示例：

H:[cancelButton(72)]-12-[acceptButton(50)]

canelButton宽72，acceptButton宽50，它们之间间距12

H:[wideView(>=60@700)]

wideView宽度大于等于60point，该约束条件优先级为700（优先级最大值为1000，优先级越高的约束越先被满足）

V:[redBox][yellowBox(==redBox)]

竖直方向上，先有一个redBox，其下方紧接一个高度等于redBox高度的yellowBox

H:|-10-[Find]-[FindNext]-[FindField(>=20)]-|

水平方向上，Find距离父view左边缘默认间隔宽度，之后是FindNext距离Find间隔默认宽度；再之后是宽度不小于20的FindField，它和FindNext以及父view右边缘的间距都是默认宽度。（竖线“|”表示superview的边缘）

VFL的使用：

使用VFL来创建约束数组+ (NSArray *)constraintsWithVisualFormat:(NSString *)format options:(NSLayoutFormatOptions)opts metrics:(NSDictionary *)metrics views:(NSDictionary *)views;format ：VFL语句opts ：约束类型metrics ：VFL语句中用到的具体数值views ：VFL语句中用到的控件创建一个字典（内部包含VFL语句中用到的控件）的快捷宏定义NSDictionaryOfVariableBindings(...)

demo示例1：

- (void)test1{    UIView *blueView = [[UIView alloc] init];    blueView.backgroundColor = [UIColor blueColor];    // 不要将AutoresizingMask转为Autolayout的约束    blueView.translatesAutoresizingMaskIntoConstraints = NO;    [self.view addSubview:blueView];        // 添加水平方向的约束    NSString *vfl = @"H:|-20-[abc]-20-|";    NSDictionary *views = @{@"abc" : blueView};    NSArray *constraints = [NSLayoutConstraint constraintsWithVisualFormat:vfl options:kNilOptions metrics:nil views:views];    [self.view addConstraints:constraints];        // 添加竖直方向的间距    NSString *vfl2 = @"V:|-20-[abc(40)]";    NSDictionary *views2 = @{@"abc" : blueView};    NSArray *constraints2 = [NSLayoutConstraint constraintsWithVisualFormat:vfl2 options:kNilOptions metrics:nil views:views2];    [self.view addConstraints:constraints2];}

效果：

demo示例2：

- (void)test2{    UIView *blueView = [[UIView alloc] init];    blueView.backgroundColor = [UIColor blueColor];    // 不要将AutoresizingMask转为Autolayout的约束    blueView.translatesAutoresizingMaskIntoConstraints = NO;    [self.view addSubview:blueView];        // 间距    NSNumber *margin = @20;        // 添加水平方向的约束    NSString *vfl = @"H:|-margin-[blueView]-margin-|";    NSDictionary *views = NSDictionaryOfVariableBindings(blueView);    NSDictionary *mertrics = NSDictionaryOfVariableBindings(margin);    NSArray *constraints = [NSLayoutConstraint constraintsWithVisualFormat:vfl options:kNilOptions metrics:mertrics views:views];    [self.view addConstraints:constraints];        // 添加竖直方向的间距    NSNumber *height = @40;    NSString *vfl2 = @"V:|-margin-[blueView(height)]";    NSDictionary *mertrics2 = NSDictionaryOfVariableBindings(margin, height);    NSArray *constraints2 = [NSLayoutConstraint constraintsWithVisualFormat:vfl2 options:kNilOptions metrics:mertrics2 views:views];    [self.view addConstraints:constraints2];}

效果：

demo示例3：

-(void)test3{    UIView *blueView = [[UIView alloc] init];    blueView.backgroundColor = [UIColor blueColor];    // 不要将AutoresizingMask转为Autolayout的约束    blueView.translatesAutoresizingMaskIntoConstraints = NO;    [self.view addSubview:blueView];        UIView *redView = [[UIView alloc] init];    redView.backgroundColor = [UIColor redColor];    // 不要将AutoresizingMask转为Autolayout的约束    redView.translatesAutoresizingMaskIntoConstraints = NO;    [self.view addSubview:redView];        // 间距    NSNumber *margin = @20;        // 添加水平方向的约束    NSString *vfl = @"H:|-margin-[blueView]-margin-[redView(==blueView)]-margin-|";    NSDictionary *views = NSDictionaryOfVariableBindings(blueView, redView);    NSDictionary *mertrics = NSDictionaryOfVariableBindings(margin);    NSArray *constraints = [NSLayoutConstraint constraintsWithVisualFormat:vfl options:NSLayoutFormatAlignAllTop | NSLayoutFormatAlignAllBottom metrics:mertrics views:views];    [self.view addConstraints:constraints];        // 添加竖直方向的间距    NSNumber *height = @40;    NSString *vfl2 = @"V:[blueView(height)]-margin-|";    NSDictionary *mertrics2 = NSDictionaryOfVariableBindings(margin, height);    NSArray *constraints2 = [NSLayoutConstraint constraintsWithVisualFormat:vfl2 options:kNilOptions metrics:mertrics2 views:views];    [self.view addConstraints:constraints2];

效果：

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