ios - Programatically autolayout not centering vertically -

i want use autolayout center view vertically , horizontally somehow i'm having troubles doing so. i'm running on ios8 simulator , ios8 device. there 2 versions of code have tried , none of them works. below snippets:

first let's allocate view we're using:

uiview *inputview = uiview.new; //don't hate me dot syntax :) inputview.translatesautoresizingmaskintoconstraints = no; inputview.backgroundcolor = uicolor.redcolor;  [self.view addsubview:inputview]; 

attempt #1:

nslayoutconstraint *constraint = [nslayoutconstraint constraintwithitem:inputview attribute:nslayoutattributecenterx relatedby:nslayoutrelationequal toitem:self.view attribute:nslayoutattributecenterx multiplier:1.0f constant:0.0f]; //center view horizontally [self.view addconstraint:constraint];  constraint = [nslayoutconstraint constraintwithitem:inputview attribute:nslayoutattributewidth relatedby:nslayoutrelationequal toitem:self.view attribute:nslayoutattributewidth multiplier:1.0f constant:0.0f]; //and make have same width view [self.view addconstraint:constraint];  constraint = [nslayoutconstraint constraintwithitem:inputview attribute:nslayoutattributeheight relatedby:nslayoutrelationequal toitem:nil attribute:nslayoutattributenotanattribute multiplier:0.0f constant:260.0f]; //force 260pts view height [inputview addconstraint:constraint]; //if add self.view it's same thing  constraint = [nslayoutconstraint constraintwithitem:inputview attribute:nslayoutattributecentery relatedby:nslayoutrelationequal toitem:self.view attribute:nslayoutattributecentery multiplier:0.5f constant:0.0f]; //and try center vertically - not work... wtf [self.view addconstraint:constraint]; 

seems legitimate piece of code me. nope.

attempt #2. it's same thing less lines of code.

nsarray *constraints = [nslayoutconstraint constraintswithvisualformat:@"|-[inputview(>=320)]-|" options:nslayoutformatalignallcenterx metrics:nil views:nsdictionaryofvariablebindings(inputview)]; [self.view addconstraints:constraints];  constraints = [nslayoutconstraint constraintswithvisualformat:@"v:|-[inputview(260)]-|" options:nslayoutformatalignallcentery metrics:nil views:nsdictionaryofvariablebindings(inputview)]; [self.view addconstraints:constraints]; 

now 1 not work either. mean center view horizontally when add vertical constraint warning telling me suck @ auto layout. says unable satisfy constraints. more specifically:

(     "<nslayoutconstraint:0x17408be00 uiview:0x174197010.top == uiview:0x174196da0.topmargin>",     "<nslayoutconstraint:0x17408bdb0 v:[uiview:0x174197010(260)]>",     "<nslayoutconstraint:0x17408bd60 uiview:0x174196da0.bottommargin == uiview:0x174197010.bottom>",     "<nslayoutconstraint:0x17008a000 'uiview-encapsulated-layout-height' v:[uiview:0x174196da0(667)]>" )  attempt recover breaking constraint  <nslayoutconstraint:0x17408bd60 uiview:0x174196da0.bottommargin == uiview:0x174197010.bottom> 

i'm not sure how fix this. below pictures of results attempts #1 , #2.

how can fix it?

while setting vertical constraint, made multiplier 0.5f causing this. make 1.0f had horizontal constraint.

constraint = [nslayoutconstraint constraintwithitem:inputview                                           attribute:nslayoutattributecentery                                           relatedby:nslayoutrelationequal                                              toitem:self.view                                           attribute:nslayoutattributecentery                                          multiplier:1.0f                                            constant:0.0f];