ios - UIImageView finding how much is out of bounds -

i'm scaling image within uiimageview using : uiviewcontentmodescaleaspectfill

the image scales nicely issue imageview sits within uiscrollview, i've set origin 0,0. fine majority of images i'm using have greater height , push out of bounds. don't want trim image, i'd dynamically push uiimageview frame down on y axis based off amount that's out of bounds.

how can go finding out what's out of bounds on y axis / height? excuse poor code example.

nsstring *imageurl = [self.detailitem objectforkey:@"job_header"];          animage = [[uiimageview alloc] initwithframe:cgrectmake(0, 0, max_height, 118)];         animage.contentmode = uiviewcontentmodescaleaspectfill;         [animage setimagewithurl:[nsurl urlwithstring:imageurl] placeholderimage:[uiimage imagenamed:@"placeholder.png"] completed:^(uiimage *image, nserror *error, sdimagecachetype cachetype) {              //adjust frame once image loaded              [self adjustpositions];         }]; 

within adjustposition:

if (animage.image.size.height > max_height) {     cgrect myframe = animage.frame;     myframe.origin.y = 100;     myframe.origin.y = animage.frame.size.height / animage.image.size.height;     animage.frame = myframe; } 

i'm using: sdwebimage, , q relevant , may explain issue little bit better: uiimageview, setclipstobounds , how images losing head

please note don't want clip bounds @ all. want preserve bounds , move origin true (0,0) position.

here method can calculate size of image in image view. originalsize size of image , constraint image view size.

- (cgsize) size: (cgsize) originalsize constrainedtosize: (cgsize) constraint {     cgfloat ratiooriginal = originalsize.width/originalsize.height;     cgfloat ratioconstraint = constraint.width/constraint.height;      cgsize resultingsize = cgsizezero;      if (ratioconstraint >= ratiooriginal) {             resultingsize = cgsizemake(constraint.width, originalsize.height*constraint.width/originalsize.width);     }else{             resultingsize = cgsizemake(constraint.height*originalsize.width/originalsize.height, constraint.height);     }      return resultingsize; } 

having size of image in image view can calculate how of image out of bounds.