来自代码的NSLayoutConstraints

Question

I have the next problem: I have an undefined number of UILabels, there might be 2 labels or 10 labels, and i add them at runtime. and i want those labels to appear in the view in two columns. I want to do this with NSLayoutConstraints. if i have just 2 labels i managed to do it, but if there are more it just doesn't work. I add the labels in a for loop. Can anybody help me? And one more question: if i have this code:

[myView addConstraints:[NSLayoutConstraint 
constraintsWithVisualFormat:@"H:|-0-[label1(label2)]-[separator(1)]-[label2]-0-|"
                                                                   options:0
                                                                   metrics:nil
                                                                     views:views]];

what does [label1(label2)] mean? Thank you

Answer 1

H:|-0-[label1(label2)]-[separator(1)]-[label2]-0-|

1.H:means horizontal

2.| means the edge of parent View

3.[] means it's have a subview inside, in this case , subview is label1.

4.- means connect

5.-number- means padding number point

6.all the subview like (label1, separator, label2) must be the key of views(last params)

7.() means the width/height of the subview.like [subview(100)] means subview's width = 100

see

[document] https://developer.apple.com/library/ios/documentation/UserExperience/Conceptual/AutolayoutPG/VisualFormatLanguage/VisualFormatLanguage.html#//apple_ref/doc/uid/TP40010853-CH3

Answer 2

what does [label1(label2)] mean? Thank you

it's mean label1 equal label2 (if prefix H - width, if prefix V - height)