这一次学习一下 updateConstraints 和 remakeConstraints
先看一下 updateConstraints ，我们做一个能够放大的按钮来实验一下
|
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 |
- (void)updateConstraints{ self.growingButton = [UIButton buttonWithType:UIButtonTypeSystem]; [self.growingButton setTitle:@"点我放大" forState:UIControlStateNormal]; self.growingButton.layer.borderColor = UIColor.greenColor.CGColor; self.growingButton.layer.borderWidth = 3; [self.growingButton addTarget:self action:@selector(onGrowButtonTaped:) forControlEvents:UIControlEventTouchUpInside]; [self.view addSubview:self.growingButton]; //记录增加的量 self.scacle = 1.0; [self.growingButton mas_updateConstraints:^(MASConstraintMaker *make) { //让按钮始终居中 make.center.mas_equalTo(self.view); // 初始宽、高为100，优先级最低，就可以保证宽高不能超过屏幕。 make.width.height.mas_equalTo(100 * self.scacle).priorityLow(); // 最大放大到整个view make.width.height.lessThanOrEqualTo(self.view); }]; } - (void)updateViewConstraints { [self.growingButton mas_updateConstraints:^(MASConstraintMaker *make) { make.center.mas_equalTo(self.view); // 初始宽、高为100，优先级最低 make.width.height.mas_equalTo(100 * self.scacle).priorityLow(); // 最大放大到整个view make.width.height.lessThanOrEqualTo(self.view); }]; [super updateViewConstraints]; } - (void)onGrowButtonTaped:(UIButton *)sender { self.scacle += 0.5; // 告诉self.view约束需要更新，这个比较重要 [self.view setNeedsUpdateConstraints]; // 调用此方法告诉self.view检测是否需要更新约束，若需要则更新，下面添加动画效果才起作用 [self.view updateConstraintsIfNeeded]; [UIView animateWithDuration:0.3 animations:^{ //我们要使约束立即生效，就必须调用layoutIfNeeded此方法 [self.view layoutIfNeeded]; }]; } |
效果就是每次你点击按钮的时候都会变大
再看一下 remakeConstraints
|
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 |
- (void)remarkConstraints{ self.remarkButton = [UIButton buttonWithType:UIButtonTypeSystem]; [self.remarkButton setTitle:@"点我展开" forState:UIControlStateNormal]; self.remarkButton.layer.borderColor = UIColor.greenColor.CGColor; self.remarkButton.layer.borderWidth = 3; self.remarkButton.backgroundColor = [UIColor lightGrayColor]; [self.remarkButton addTarget:self action:@selector(onGrowButtonTaped:) forControlEvents:UIControlEventTouchUpInside]; [self.view addSubview:self.remarkButton]; self.isExpanded = NO; [self.remarkButton mas_remakeConstraints:^(MASConstraintMaker *make) { make.top.mas_equalTo(0); make.left.right.mas_equalTo(0); make.bottom.mas_equalTo(-350); }]; } - (void)updateViewConstraints { // 这里使用update也是一样的。 // remake会将之前的全部移除，然后重新添加 WS(weakSelf); [self.remarkButton mas_remakeConstraints:^(MASConstraintMaker *make) { make.top.mas_equalTo(0); make.left.right.mas_equalTo(0); if (weakSelf.isExpanded) { make.bottom.mas_equalTo(0); } else { make.bottom.mas_equalTo(-350); } }]; [super updateViewConstraints]; } - (void)onGrowButtonTaped:(UIButton *)sender { self.isExpanded = !self.isExpanded; if (!self.isExpanded) { [self.remarkButton setTitle:@"点我展开" forState:UIControlStateNormal]; } else { [self.remarkButton setTitle:@"点我收起" forState:UIControlStateNormal]; } // 告诉self.view约束需要更新，这个比较重要 [self.view setNeedsUpdateConstraints]; // 调用此方法告诉self.view检测是否需要更新约束，若需要则更新，下面添加动画效果才起作用 [self.view updateConstraintsIfNeeded]; [UIView animateWithDuration:0.3 animations:^{ //我们要使约束立即生效，就必须调用layoutIfNeeded此方法 [self.view layoutIfNeeded]; }]; } |
来看一下效果
这里就是说明一下我们之前提到的
mas_makeConstraints 只负责新增约束 Autolayout不能同时存在两条针对于同一对象的约束 否则会报错
mas_updateConstraints 针对上面的情况 会更新在block中出现的约束 不会导致出现两个相同约束的情况
mas_remakeConstraints 则会清除之前的所有约束 仅保留最新的约束
代码请查看 http://git.oschina.net/zcb1603999/DCTest
转载请注明：怼码人生 » iOS自动布局之Masonry第三弹
