我的视图上有一个UILabel和一个UIButton。当点击按钮时,UILabel应该根据标签内容进行动画高度变化。我尝试了以下代码:
- (void)viewDidLoad {
self.textLabel= [[UILabel alloc] initWithFrame:CGRectZero];
self.textLabel.numberOfLines=0;
self.textLabel.font= [UIFont systemFontOfSize:14];
self.textLabel.backgroundColor= [UIColor lightGrayColor];
self.textLabel.text= @"short text";
[self.view addSubview:self.textLabel];
[self.textLabel setTranslatesAutoresizingMaskIntoConstraints:NO];
[self.view addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"H:|-10-[_textLabel]-10-|"
options:0
metrics:nil
views:NSDictionaryOfVariableBindings(_textLabel)]];
self.button= [UIButton buttonWithType:UIButtonTypeSystem];
[self.button addTarget:self action:@selector(buttonTouched:) forControlEvents:UIControlEventTouchUpInside];
[self.button setTitle:@"Tap" forState:UIControlStateNormal];
self.button.backgroundColor= [UIColor greenColor];
[self.button setTranslatesAutoresizingMaskIntoConstraints:NO];
[self.view addSubview:self.button];
[self.view addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"H:|-10-[_button]-10-|"
options:0
metrics:nil
views:NSDictionaryOfVariableBindings(_button)]];
[self.view addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"V:|-50-[_textLabel(>=0)]-10-[_button(==20)]"
options:0
metrics:nil
views:NSDictionaryOfVariableBindings(_textLabel,_button)]];
}
- (void)buttonTouched:(id)buttonTouched {
self.shortText =!self.shortText;
self.textLabel.text= self.shortText ?@"short text":@"long long long text\nlong long long text\nlong long long text\n";
[UIView animateWithDuration:1.0
animations:^{
[self.view layoutIfNeeded];
}];
}