需求：uiimage根据屏幕宽度按照自己本身比例改变高度
上代码，为uiimage创建一个category
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#import "uiimage+uiimageextras.h"
@implementation uiimage (uiimageextras)
- (uiimage *)imagebyscalingtosize:(cgsize)targetsize
{
uiimage *sourceimage = self;
uiimage *newimage = nil;
cgsize imagesize = sourceimage.size;
cgfloat width = imagesize.width;
cgfloat height = imagesize.height;
cgfloat targetwidth = targetsize.width;
cgfloat targetheight = targetsize.height;
cgfloat scalefactor = 0.0;
cgfloat scaledwidth = targetwidth;
cgfloat scaledheight = targetheight;
cgpoint thumbnailpoint = cgpointmake(0.0,0.0);
if (cgsizeequaltosize(imagesize, targetsize) ==no) {
cgfloat widthfactor = targetwidth / width;
cgfloat heightfactor = targetheight / height;
if (widthfactor < heightfactor)
scalefactor = widthfactor;
else
scalefactor = heightfactor;
scaledwidth = width * scalefactor;
scaledheight = height * scalefactor;
// center the image
if (widthfactor < heightfactor) {
thumbnailpoint.y = (targetheight - scaledheight) * 0.5;
} else if (widthfactor > heightfactor) {
thumbnailpoint.x = (targetwidth - scaledwidth) * 0.5;
}
}
// this is actually the interesting part:
uigraphicsbeginimagecontext(targetsize);
cgrect thumbnailrect = cgrectzero;
thumbnailrect.origin = thumbnailpoint;
thumbnailrect.size.width = scaledwidth;
thumbnailrect.size.height = scaledheight;
[sourceimage drawinrect:thumbnailrect];
newimage =uigraphicsgetimagefromcurrentimagecontext();
uigraphicsendimagecontext();
if(newimage == nil)
nslog(@"could not scale image");
return newimage ;
}
@end
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在需要使用的地方import然后使用
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cgsize size = image.size;
image = [image imagebyscalingtosize:cgsizemake([uiscreen mainscreen].bounds.size.width,[uiscreen mainscreen].bounds.size.width * (size.height / size.width))];
self.imageview.image = image;
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以上所述是小编给大家介绍的ios uiimage根据屏宽调整size的实例代码，希望对大家有所帮助，如果大家有任何疑问请给我留言，小编会及时回复大家的。在此也非常感谢大家对服务器之家网站的支持！
原文链接：http://blog.csdn.net/u012265444/article/details/54598873