- secureTextEntry
rawVaule
Int?:必须使用!拆包(取值)
Int!:自动拆包(取值)
2.值传递时复制值,只可以变
引用传递值时,只不变
conficting:冲突
missing:丢失
spacing:间距,最近的邻居
width/height
Equal widths/heights:比例
Aspect ratio:宽高比
Align:对齐
Leading Edges 左对齐
Trailing Edges 右对齐
Top Edges 上对齐
Bottom Edges 下对齐
Horizontal Centers 水平居中对齐
Vertical Centers 垂直居中对齐
BaseLines
Horizontal Center in Container 水平居中
Vertical Center in Container 垂直居中