ios - scrollView: how to create a pure auto layout scrollview with paging? -
can tell me did wrong here... - pin uiscrollview container view - pin subviews onto uiscrollview
after reading apple technote it, tried both hybrid method , pure auto layout method. hybrid method using nib works awful paging, looks big picture in scrollview, rather paged.
i created pure auto layout version in code, uiscrollview subview of uiview. time view stuck, , uiimage gigantic, full size:
//scroll view if (self.scrollview == nil) { self.scrollview = [[uiscrollview alloc] initwithframe:self.frame]; self.scrollview.translatesautoresizingmaskintoconstraints = no; [self.scrollview setclipstobounds:no]; [self.scrollview setpagingenabled:yes]; [self addsubview: self.scrollview]; [self addconstraints: [nslayoutconstraint constraintswithvisualformat:@"h:|[scrollview(300)]|" options:0 metrics:nil views:@{@"scrollview":self.scrollview}]]; [self addconstraints: [nslayoutconstraint constraintswithvisualformat:@"v:|[scrollview(300)]|" options:0 metrics:nil views:@{@"scrollview":self.scrollview}]]; -(void) createcontentview { (int i=0; i<self.pageimages.count; i++) { uilabel* toplabel = [[uilabel alloc] init]; toplabel.text = [nsstring stringwithformat:@"toplabel %d", i+1]; [toplabel sizetofit]; [self.toplabelarray insertobject:toplabel atindex:i]; [self.scrollview addsubview:toplabel]; toplabel.translatesautoresizingmaskintoconstraints = no; uilabel* bottomlabel = [[uilabel alloc] init]; bottomlabel.text = [nsstring stringwithformat:@"bottomlabel %d", i+1]; [bottomlabel sizetofit]; [self.bottomlabelarray insertobject:bottomlabel atindex:i]; [self.scrollview addsubview:bottomlabel]; bottomlabel.translatesautoresizingmaskintoconstraints = no; uibutton* button = [[uibutton alloc] init]; button.titlelabel.text = [nsstring stringwithformat:@"button %d", i+1]; [button sizetofit]; [self.buttonarray insertobject:button atindex:i]; [self.scrollview addsubview:button]; button.translatesautoresizingmaskintoconstraints = no; uiimageview* imageview = [[uiimageview alloc] initwithimage:[uiimage imagenamed:[self.pageimages objectatindex:i]]]; imageview.frame = cgrectmake(0,0,200,200); imageview.translatesautoresizingmaskintoconstraints = no; imageview.contentmode = uiviewcontentmodescaleaspectfit; [self.pageviews insertobject:imageview atindex:i]; [self.scrollview addsubview:imageview]; nsdictionary* viewsdictionary = @{@"toplabel":toplabel, @"bottomlabel":bottomlabel, @"button": button, @"imageview": imageview }; [self.scrollview addconstraints: [nslayoutconstraint constraintswithvisualformat:@"v:|-(10)-[toplabel]-(10)-[imageview]-(10)-[bottomlabel]-(10)-|" options:0 metrics:nil views:viewsdictionary]]; [self.scrollview addconstraints: [nslayoutconstraint constraintswithvisualformat:@"v:[button]-(10)-|" options:0 metrics:nil views:viewsdictionary]]; if (i==0) { [self.scrollview addconstraints: [nslayoutconstraint constraintswithvisualformat:@"h:|-(10)-[toplabel]" options:0 metrics:nil views:viewsdictionary]]; [self.scrollview addconstraints: [nslayoutconstraint constraintswithvisualformat:@"h:|-(10)-[imageview]" options:0 metrics:nil views:viewsdictionary]]; [self.scrollview addconstraints: [nslayoutconstraint constraintswithvisualformat:@"h:|-(10)-[bottomlabel]-(10)-[button]" options:0 metrics:nil views:viewsdictionary]]; } else if (i == self.pageimages.count) { [self.scrollview addconstraints: [nslayoutconstraint constraintswithvisualformat:@"h:-(10)-[toplabel]-(10)-|" options:0 metrics:nil views:viewsdictionary]]; [self.scrollview addconstraints: [nslayoutconstraint constraintswithvisualformat:@"h:-(10)-[imageview]-(10)-|" options:0 metrics:nil views:viewsdictionary]]; [self.scrollview addconstraints: [nslayoutconstraint constraintswithvisualformat:@"h:-(10)-[bottomlabel]-(10)-[button]-(10)-|" options:0 metrics:nil views:viewsdictionary]]; } else { [self.scrollview addconstraints: [nslayoutconstraint constraintswithvisualformat:@"h:[prevtoplabel]-(10)-[toplabel]" options:0 metrics:nil views:@{@"prevtoplabel": [self.toplabelarray objectatindex: i-1], @"toplabel": toplabel }]]; [self.scrollview addconstraints: [nslayoutconstraint constraintswithvisualformat:@"h:[previmageview]-(10)-[imageview]" options:0 metrics:nil views:@{@"previmageview": [self.pageviews objectatindex: i-1], @"imageview": imageview }]]; [self.scrollview addconstraints: [nslayoutconstraint constraintswithvisualformat:@"h:[prevbutton]-(10)-[bottomlabel]-(10)-[button]" options:0 metrics:nil views:@{@"prevbutton": [self.buttonarray objectatindex: i-1], @"button":button, @"bottomlabel": bottomlabel }]]; } [self.scrollview addconstraint:[nslayoutconstraint constraintwithitem:toplabel attribute:nslayoutattributecenterx relatedby:nslayoutrelationequal toitem:imageview attribute:nslayoutattributecenterx multiplier:1 constant:0.0]]; [self.scrollview addconstraint:[nslayoutconstraint constraintwithitem:bottomlabel attribute:nslayoutattributecenterx relatedby:nslayoutrelationequal toitem:imageview attribute:nslayoutattributecenterx multiplier:0.8 constant:0.0]]; // [self.scrollview addconstraint:[nslayoutconstraint //
ok, there's few things wrong here:
else if (i == self.pageimages.count)
this clause never run, loop count set break when i == self.pageimages.count -1, here for (int i=0; i<self.pageimages.count; i++).
next
[self.scrollview addconstraints: [nslayoutconstraint constraintswithvisualformat:@"h:-(10)-[toplabel]-(10)-|" options:0 metrics:nil views:viewsdictionary]]; [self.scrollview addconstraints: [nslayoutconstraint constraintswithvisualformat:@"h:-(10)-[imageview]-(10)-|" options:0 metrics:nil views:viewsdictionary]]; [self.scrollview addconstraints: [nslayoutconstraint constraintswithvisualformat:@"h:-(10)-[bottomlabel]-(10)-[button]-(10)-|" options:0 metrics:nil views:viewsdictionary]]; these produce invalid constraints, @"h:-(10)-[bottomlabel].... not pinning furthest left constraint anything. visual format strings connect views need start or finish view. either subview ([subview]) or superview (|). fix this, need keep reference previous pages label in loop, , add beginning of vfl string. this
@"h:[prevbottomlabel]-(10)-[bottomlabel].... prevbottomlabel = bottomlabel; // continue loop next:
uiimageview* imageview = [[uiimageview alloc] initwithimage:[uiimage imagenamed:[self.pageimages objectatindex:i]]]; imageview.frame = cgrectmake(0,0,200,200); imageview.translatesautoresizingmaskintoconstraints = no; imageview.contentmode = uiviewcontentmodescaleaspectfit; this not have desired effect, can't manually set frame, switch on autolayout. currently, frame value ignored, , height , width set intrinsic content size of image view, height , width of image. if want set height , width, need constraints, so:
[imageview addconstraints: [nslayoutconstraint constraintswithvisualformat:@"h:[imageview(200)]" options:0 metrics:nil views:viewsdictionary]]; [imageview addconstraints: [nslayoutconstraint constraintswithvisualformat:@"v:[imageview(200)]" options:0 metrics:nil views:viewsdictionary]]; that should give pointers, there may other mistakes in there fixing these place start.
Comments
Post a Comment