先来看看实现效果(gif):
实现思路:
直接自定义 uiview(cyphotopreviewer),为了实现双击缩放,可以实现 uiscrollviewdelegate 对应的方法。如果需要模糊背景,可以在自定义的 uiview 中先添加模糊背景,再添加 uiscrollview,继而在 uiscrollview 中添加图片容器,这个容器就是要显示的图片的 superview,代码一目了然:
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- ( void )setup {
self.frame = [uiscreenmainscreen].bounds;
self.backgroundcolor = [uicolorclearcolor];
uitapgesturerecognizer *singletap = [[uitapgesturerecognizeralloc] initwithtarget:selfaction:@selector(singletap:)];
[self addgesturerecognizer:singletap];
uitapgesturerecognizer *doubletap = [[uitapgesturerecognizeralloc] initwithtarget:selfaction:@selector(doubletap:)];
doubletap.numberoftapsrequired = 2;
[singletaprequiregesturerecognizertofail:doubletap];
[self addgesturerecognizer:doubletap];
uilongpressgesturerecognizer *longpress = [[uilongpressgesturerecognizeralloc] initwithtarget:selfaction:@selector(longpress:)];
[self addgesturerecognizer:longpress];
// 设置模糊背景
self.blurbackground = [[uivisualeffectviewalloc] initwitheffect:[uiblureffecteffectwithstyle:uiblureffectstyleextralight]];
self.blurbackground.frame = self.frame;
[self addsubview:self.blurbackground];
// 设置 uiscrollview 相关属性
self.scrollview = [[uiscrollviewalloc] initwithframe:[uiscreenmainscreen].bounds];
self.scrollview.delegate = self;
self.scrollview.bounceszoom = yes;
self.scrollview.maximumzoomscale = 3.0;
self.scrollview.multipletouchenabled = yes;
self.scrollview.alwaysbouncevertical = no;
self.scrollview.showsverticalscrollindicator = no;
self.scrollview.showshorizontalscrollindicator = no;
[self addsubview:self.scrollview];
// containerview
self.containerview = [[uiviewalloc] init];
[self.scrollviewaddsubview:self.containerview];
// imageview
self.imageview = [[uiimageviewalloc] init];
self.imageview.clipstobounds = yes;
self.imageview.backgroundcolor = [uicolorcolorwithwhite:1.0 alpha:0.5];
[self.containerviewaddsubview:self.imageview];
}
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可以看到,我们给设置了模糊背景,给这个 cyphotopreviewer 添加了单击手势(关闭 photopreviewer)、双击手势(缩放图片)、长按手势(使用 uialertcontroller 菜单,比如保存图片等)。
好,确定了这个 cyphotopreviewer 中的显示内容,那么我们该如何显示这个 cyphotopreviewer 呢?
- 直接将这个 cyphotopreviewer 添加到 keywindow 上
- 将这个 cyphotopreviewer 添加到控制器的 self.view 上
这两种方式的实现都差不多,不过如果使用第一种方式的话,会导致将 cyphotopreviewer 添加到 keywindow 上之后,再长按继续将 uialertcontroller 显示就比较麻烦了,因此,这里打算采用将 cyphotopreviewer 添加到控制器的 self.view
上,继而就可以很方便的显示 uialertcontroller 了:
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- ( void )previewfromimageview:(uiimageview *)fromimageviewincontainer:(uiview *)container {
_fromimageview = fromimageview;
fromimageview.hidden = yes;
[containeraddsubview:self]; // 将 cyphotopreviewer 添加到 container 上
self.containerview.origin = cgpointzero;
self.containerview.width = self.width; // containerview 的宽度是屏幕的宽度
uiimage *image = fromimageview.image;
// 计算 containerview 的高度
if (image.size.height / image.size.height > self.height / self.width) {
self.containerview.height = floor (image.size.height / (image.size.width / self.width));
} else {
cgfloatheight = image.size.height / image.size.width * self.width;
if (height self.height && self.containerview.height - self.height
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可以看到,我们将外面的图片 fromimageview 传递进来,是为了显示更好的动画效果;将控制器的 container(self.view)
传递进来,是为了将 cyphotopreviewer 添加到 container 的细节不需要在调用处处理,即初始化 cyphotopreviewer 之后,cyphotopreviewer 就直接被 container 添加为 subview 了。动画很简单不再细说。
显示的效果已经做好,单击关闭 cyphotopreviewer 也比较好实现,只需要从父类移除 cyphotopreviewer 即可:
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- ( void )dismiss {
[uiviewanimatewithduration:0.18 delay:0.0 options:uiviewanimationoptioncurveeaseinoutanimations:^{
cgrectfromrect = [self.fromimageviewconvertrect:self.fromimageview.boundstoview:self.containerview];
self.imageview.contentmode = self.fromimageview.contentmode;
self.imageview.frame = fromrect;
self.blurbackground.alpha = 0.01;
} completion:^( bool finished) {
[uiviewanimatewithduration:0.10 delay:0 options:uiviewanimationoptioncurveeaseinoutanimations:^{
self.fromimageview.hidden = no;
self.alpha = 0;
} completion:^( bool finished) {
[self removefromsuperview];
}];
}];
}
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好了,显示和关闭 cyphotopreviewer 都实现了,如果需要双击缩放图片效果,就得实现 uiscrollviewdelegate 的两个方法以及 cyphotopreviewer 的双击手势:
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- (uiview *)viewforzoominginscrollview:(uiscrollview *)scrollview{
return self.containerview;
}
- ( void )scrollviewdidzoom:(uiscrollview *)scrollview {
uiview *subview = self.containerview;
cgfloatoffsetx = (scrollview.bounds.size.width > scrollview.contentsize.width)?
(scrollview.bounds.size.width - scrollview.contentsize.width) * 0.5 : 0.0;
cgfloatoffsety = (scrollview.bounds.size.height > scrollview.contentsize.height)?
(scrollview.bounds.size.height - scrollview.contentsize.height) * 0.5 : 0.0;
subview.center = cgpointmake(scrollview.contentsize.width * 0.5 + offsetx,
scrollview.contentsize.height * 0.5 + offsety);
}
- ( void )doubletap:(uitapgesturerecognizer *)recognizer {
if (self.scrollview.zoomscale > 1.0) {
[self.scrollviewsetzoomscale:1.0 animated:yes];
} else {
cgpointtouchpoint = [recognizerlocationinview:self.imageview];
cgfloatnewzoomscale = self.scrollview.maximumzoomscale;
cgfloatxsize = self.width / newzoomscale;
cgfloatysize = self.height / newzoomscale;
[self.scrollviewzoomtorect:cgrectmake(touchpoint.x - xsize / 2, touchpoint.y - ysize / 2, xsize, ysize) animated:yes];
}
}
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最后一个就是长按弹出菜单(uialertcontroller)了:
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- ( void )longpress:(uilongpressgesturerecognizer *)recognizer {
// 为了避免弹警告:warning: attempt to present on which is already presenting ,最好加入状态判断
if (recognizer.state == uigesturerecognizerstatebegan) {
uialertcontroller *alertcontroller = [uialertcontrolleralertcontrollerwithtitle:@ "quoradots" message:nilpreferredstyle:uialertcontrollerstyleactionsheet];
[alertcontrolleraddaction:[uialertactionactionwithtitle:@ "保存" style:uialertactionstyledefaulthandler:nil]];
[alertcontrolleraddaction:[uialertactionactionwithtitle:@ "取消" style:uialertactionstylecancelhandler:nil]];
uiviewcontroller *vc = self.viewcontroller;
[vcpresentviewcontroller:alertcontrolleranimated:yescompletion:nil];
}
}
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注意一点, longpress:
这个方法会调用很频繁,因此,为了避免 attempt to present xxx on xxx which is already presenting xxx 这个警告,我们需要判断手势的状态。
后话:
这个只是显示单张图片的大图,如果需要显示多张图片类似微信微博的九宫格图片的大图显示,则需要将这个 cyphotopreviewer 搞成 uicollectionview 的 item 即可,大家可以尝试尝试。
好了,以上就是这篇文章的全部内容了,希望本文的内容对各位ios开发者们能带来一定的帮助,如果有疑问大家可以留言交流,谢谢大家对服务器之家的支持。