// 系统的约束代码
@implementation ViewController
- (void)viewDidLoad {
[super viewDidLoad];
UIView *superView = self.view;
UIView *viewDemo = [[UIView alloc] init];
viewDemo.translatesAutoresizingMaskIntoConstraints = NO;
viewDemo.backgroundColor = [UIColor orangeColor];
[superView addSubview:viewDemo];
UIEdgeInsets padding = UIEdgeInsetsMake(, , , );
[superView addConstraints:@[
// viewDemo顶部距离父视图superView顶部距离为padding.top(即为：10)，
[NSLayoutConstraint constraintWithItem:viewDemo attribute:NSLayoutAttributeTop relatedBy:NSLayoutRelationEqual toItem:superView attribute:NSLayoutAttributeTop multiplier: constant:padding.top],
[NSLayoutConstraint constraintWithItem:viewDemo attribute:NSLayoutAttributeLeft relatedBy:NSLayoutRelationEqual toItem:superView attribute:NSLayoutAttributeLeft multiplier: constant:padding.left],
[NSLayoutConstraint constraintWithItem:viewDemo attribute:NSLayoutAttributeRight relatedBy:NSLayoutRelationEqual toItem:superView attribute:NSLayoutAttributeRight multiplier: constant:-padding.right],
[NSLayoutConstraint constraintWithItem:viewDemo attribute:NSLayoutAttributeBottom relatedBy:NSLayoutRelationEqual toItem:superView attribute:NSLayoutAttributeBottom multiplier: constant:-padding.bottom]
]];
}
// 注：若是把右边约束去掉，改为如下语句
// [NSLayoutConstraint constraintWithItem:viewDemo attribute:NSLayoutAttributeWidth relatedBy:NSLayoutRelationEqual toItem:superView attribute:NSLayoutAttributeWidth multiplier:0.5 constant:0]
// 则viewDemo的宽度变为superView的0.5倍！！
//***************************************************
// VFL语言
UIView *viewLeft = [[UIView alloc] init];
viewLeft.translatesAutoresizingMaskIntoConstraints = NO;
viewLeft.backgroundColor = [UIColor orangeColor];
[self.view addSubview:viewLeft];
UIView *viewRight = [[UIView alloc] init];
viewRight.translatesAutoresizingMaskIntoConstraints = NO;
viewRight.backgroundColor = [UIColor redColor];
[self.view addSubview:viewRight];
// horizontal：水平方向距左边10，距右边10
//简单说来，NSDictionaryOfVariableBindings(scrollView)就等于@{@”scrollView”: scrollView}
NSDictionary *constraintDict = NSDictionaryOfVariableBindings(viewLeft,viewRight);
NSArray *hConstraintArrayLeft = [NSLayoutConstraint constraintsWithVisualFormat:@"H:|-(10)-[viewLeft]-(10)-|" options: metrics:nil views:constraintDict];
// vertical： 垂直方向距顶部30，控件高度100
NSArray *vConstraintArrayLeft = [NSLayoutConstraint constraintsWithVisualFormat:@"V:|-(30)-[viewLeft(100)]" options: metrics:nil views:constraintDict];
// 添加到父视图上
[self.view addConstraints:hConstraintArrayLeft];
[self.view addConstraints:vConstraintArrayLeft];
NSArray *hConstraintArrayRight = [NSLayoutConstraint constraintsWithVisualFormat:@"H:|-(10)-[viewRight]-(10)-|" options: metrics:nil views:constraintDict];
// viewRight距viewLeft的垂直距离为50
NSArray *vConstraintArrayRight = [NSLayoutConstraint constraintsWithVisualFormat:@"V:[viewLeft]-(50)-[viewRight(200)]" options: metrics:nil views:constraintDict];
[self.view addConstraints:hConstraintArrayRight];
[self.view addConstraints:vConstraintArrayRight];
//***************************************************
// 三方库：Masonry
// 居中
// 快速定义一个weakSelf，用于block里面，防止循环引用
#define WS(weakSelf) __weak __typeof(&*self)weakSelf = self
WS(ws);
UIView *sv = [UIView new];
sv.backgroundColor = [UIColor orangeColor];
// 在做autoLayout之前 一定要先将view添加到superView上 否则会报错
[self.view addSubview:sv];
[sv mas_makeConstraints:^(MASConstraintMaker *make) {
// 居中
make.center.equalTo(ws.view);
// 设置size
make.size.mas_equalTo(CGSizeMake(300, 300));
}];
3. [初级] 让两个高度为150的view垂直居中且等宽且等间隔排列 间隔为10(自动计算其宽度)
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int padding1 = 10;[sv2 mas_makeConstraints:^(MASConstraintMaker *make) { make.centerY.mas_equalTo(sv.mas_centerY);
make.left.equalTo(sv.mas_left).with.offset(padding1);
make.right.equalTo(sv3.mas_left).with.offset(-padding1);
make.height.mas_equalTo(@150);
make.width.equalTo(sv3);
}];[sv3 mas_makeConstraints:^(MASConstraintMaker *make) { make.centerY.mas_equalTo(sv.mas_centerY);
make.left.equalTo(sv2.mas_right).with.offset(padding1);
make.right.equalTo(sv.mas_right).with.offset(-padding1);
make.height.mas_equalTo(@150);
make.width.equalTo(sv2);
}]; |
代码效果
这里我们在两个子view之间互相设置的约束 可以看到他们的宽度在约束下自动的被计算出来了
4. [中级] 在UIScrollView顺序排列一些view并自动计算contentSize
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UIScrollView *scrollView = [UIScrollView new];
scrollView.backgroundColor = [UIColor whiteColor];[sv addSubview:scrollView];[scrollView mas_makeConstraints:^(MASConstraintMaker *make) { make.edges.equalTo(sv).with.insets(UIEdgeInsetsMake(5,5,5,5));
}];UIView *container = [UIView new];
[scrollView addSubview:container];[container mas_makeConstraints:^(MASConstraintMaker *make) { make.edges.equalTo(scrollView);
make.width.equalTo(scrollView);
}];int count = 10;UIView *lastView = nil;for ( int i = 1 ; i <= count ; ++i )
{ UIView *subv = [UIView new];
[container addSubview:subv];
subv.backgroundColor = [UIColor colorWithHue:( arc4random() % 256 / 256.0 )
saturation:( arc4random() % 128 / 256.0 ) + 0.5
brightness:( arc4random() % 128 / 256.0 ) + 0.5
alpha:1];
[subv mas_makeConstraints:^(MASConstraintMaker *make) {
make.left.and.right.equalTo(container);
make.height.mas_equalTo(@(20*i));
if ( lastView )
{
make.top.mas_equalTo(lastView.mas_bottom);
}
else
{
make.top.mas_equalTo(container.mas_top);
}
}];
lastView = subv;
}[container mas_makeConstraints:^(MASConstraintMaker *make) { make.bottom.equalTo(lastView.mas_bottom);
}]; |
头部效果
尾部效果
从scrollView的scrollIndicator可以看出 scrollView的内部已如我们所想排列好了
这里的关键就在于container这个view起到了一个中间层的作用 能够自动的计算uiscrollView的contentSize
5. [高级] 横向或者纵向等间隙的排列一组view
很遗憾 autoLayout并没有直接提供等间隙排列的方法(Masonry的官方demo中也没有对应的案例) 但是参考案例3 我们可以通过一个小技巧来实现这个目的 为此我写了一个Category
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@implementation UIView(Masonry_LJC)- (void) distributeSpacingHorizontallyWith:(NSArray*)views{ NSMutableArray *spaces = [NSMutableArray arrayWithCapacity:views.count+1];
for ( int i = 0 ; i < views.count+1 ; ++i )
{
UIView *v = [UIView new];
[spaces addObject:v];
[self addSubview:v];
[v mas_makeConstraints:^(MASConstraintMaker *make) {
make.width.equalTo(v.mas_height);
}];
}
UIView *v0 = spaces[0];
__weak __typeof(&*self)ws = self;
[v0 mas_makeConstraints:^(MASConstraintMaker *make) {
make.left.equalTo(ws.mas_left);
make.centerY.equalTo(((UIView*)views[0]).mas_centerY);
}];
UIView *lastSpace = v0;
for ( int i = 0 ; i < views.count; ++i )
{
UIView *obj = views[i];
UIView *space = spaces[i+1];
[obj mas_makeConstraints:^(MASConstraintMaker *make) {
make.left.equalTo(lastSpace.mas_right);
}];
[space mas_makeConstraints:^(MASConstraintMaker *make) {
make.left.equalTo(obj.mas_right);
make.centerY.equalTo(obj.mas_centerY);
make.width.equalTo(v0);
}];
lastSpace = space;
}
[lastSpace mas_makeConstraints:^(MASConstraintMaker *make) {
make.right.equalTo(ws.mas_right);
}];
}- (void) distributeSpacingVerticallyWith:(NSArray*)views{ NSMutableArray *spaces = [NSMutableArray arrayWithCapacity:views.count+1];
for ( int i = 0 ; i < views.count+1 ; ++i )
{
UIView *v = [UIView new];
[spaces addObject:v];
[self addSubview:v];
[v mas_makeConstraints:^(MASConstraintMaker *make) {
make.width.equalTo(v.mas_height);
}];
}
UIView *v0 = spaces[0];
__weak __typeof(&*self)ws = self;
[v0 mas_makeConstraints:^(MASConstraintMaker *make) {
make.top.equalTo(ws.mas_top);
make.centerX.equalTo(((UIView*)views[0]).mas_centerX);
}];
UIView *lastSpace = v0;
for ( int i = 0 ; i < views.count; ++i )
{
UIView *obj = views[i];
UIView *space = spaces[i+1];
[obj mas_makeConstraints:^(MASConstraintMaker *make) {
make.top.equalTo(lastSpace.mas_bottom);
}];
[space mas_makeConstraints:^(MASConstraintMaker *make) {
make.top.equalTo(obj.mas_bottom);
make.centerX.equalTo(obj.mas_centerX);
make.height.equalTo(v0);
}];
lastSpace = space;
}
[lastSpace mas_makeConstraints:^(MASConstraintMaker *make) {
make.bottom.equalTo(ws.mas_bottom);
}];
}@end |
简单的来测试一下
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UIView *sv11 = [UIView new];
UIView *sv12 = [UIView new];
UIView *sv13 = [UIView new];
UIView *sv21 = [UIView new];
UIView *sv31 = [UIView new];
sv11.backgroundColor = [UIColor redColor];sv12.backgroundColor = [UIColor redColor];sv13.backgroundColor = [UIColor redColor];sv21.backgroundColor = [UIColor redColor];sv31.backgroundColor = [UIColor redColor];[sv addSubview:sv11];[sv addSubview:sv12];[sv addSubview:sv13];[sv addSubview:sv21];[sv addSubview:sv31];//给予不同的大小 测试效果[sv11 mas_makeConstraints:^(MASConstraintMaker *make) { make.centerY.equalTo(@[sv12,sv13]);
make.centerX.equalTo(@[sv21,sv31]);
make.size.mas_equalTo(CGSizeMake(40, 40));
}];[sv12 mas_makeConstraints:^(MASConstraintMaker *make) { make.size.mas_equalTo(CGSizeMake(70, 20));
}];[sv13 mas_makeConstraints:^(MASConstraintMaker *make) { make.size.mas_equalTo(CGSizeMake(50, 50));
}];[sv21 mas_makeConstraints:^(MASConstraintMaker *make) { make.size.mas_equalTo(CGSizeMake(50, 20));
}];[sv31 mas_makeConstraints:^(MASConstraintMaker *make) { make.size.mas_equalTo(CGSizeMake(40, 60));
}];[sv distributeSpacingHorizontallyWith:@[sv11,sv12,sv13]];[sv distributeSpacingVerticallyWith:@[sv11,sv21,sv31]];[sv showPlaceHolderWithAllSubviews];[sv hidePlaceHolder]; |
代码效果
perfect! 简洁明了的达到了我们所要的效果
这里所用的技巧就是 使用空白的占位view来填充我们目标view的旁边 这点通过图上的空白标注可以看出来
引自：http://www.cocoachina.com/ios/20141219/10702.html
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