ConstraintLayout

https://medium.com/r/?url=http%3A%2F%2Fwww.jianshu.com%2Fp%2F792d2682c538

https://medium.com/r/?url=https%3A%2F%2Fcodelabs.developers.google.com%2Fcodelabs%2Fconstraint-layout%2Findex.html%230

https://medium.com/r/?url=https%3A%2F%2Fdeveloper.android.com%2Fstudio%2Fwrite%2Flayout-editor.html

https://medium.com/r/?url=http%3A%2F%2Fquanqi.org%2F2016%2F05%2F20%2Fcode-labs-constraint-layout%2F

https://medium.com/exploring-android/exploring-the-new-android-constraintlayout-eed37fe8d8f1#.l2lar665g