ios - change Auto Layout dynamically -

i have show 3 labels like

label1 | label2 | label3 //horizontally

i want these 3labels width equally divided according screen size width

how can achieve nib file directly?

thanks

question 2

label1 | label2 | lable3

//all labels widths equally

//all labels subview of view call x view

label1 : height 100

label2 : height 150

label3 : height 300

q: want x view's height max(100,150,300) = 300

just give top, left , right, height , equal width constraints label....