Masonry手寫(xiě)Autolayout專(zhuān)題
Masonry介紹與使用實(shí)踐：快速上手Autolayout
http://www.cocoachina.com/ios/20141219/10702.html
1Masonry開(kāi)發(fā)技巧
1.1簡(jiǎn)單使用技巧
1.1.1[基礎(chǔ)]居中顯示一個(gè)view
- (void)viewDidLoad
{
[superviewDidLoad];
// Do any additional setup after loading the view.
WS(ws);
UIView *sv = [UIViewnew];
[sv showPlaceHolder];
sv.backgroundColor = [UIColor blackColor];
[self.view addSubview:sv];
[sv mas_makeConstraints:^(MASConstraintMaker *make) {
make.center.equalTo(ws.view);
make.size.mas_equalTo(CGSizeMake(300, 300));
}];
}
代碼效果
使用我之間寫(xiě)的MMPlaceHolder可以看到superview已經(jīng)按照我們預(yù)期居中并且設(shè)置成了適當(dāng)?shù)拇笮?/p>
那么先看看這幾行代碼
//從此以后基本可以?huà)仐塁GRectMake了
UIView *sv = [UIViewnew];
//在做autoLayout之前一定要先將view添加到superview上否則會(huì)報(bào)錯(cuò)
[self.view addSubview:sv];
//mas_makeConstraints就是Masonry的autolayout添加函數(shù)將所需的約束添加到block中行了
[sv mas_makeConstraints:^(MASConstraintMaker *make) {
//將sv居中(很容易理解吧?)
make.center.equalTo(ws.view);
//將size設(shè)置成(300,300)
make.size.mas_equalTo(CGSizeMake(300, 300));
}];
這里有兩個(gè)問(wèn)題要分解一下
首先在Masonry中能夠添加autolayout約束有三個(gè)函數(shù)
- (NSArray *)mas_makeConstraints:(void(^)(MASConstraintMaker *make))block;
- (NSArray *)mas_updateConstraints:(void(^)(MASConstraintMaker *make))block;
- (NSArray *)mas_remakeConstraints:(void(^)(MASConstraintMaker *make))block;
/*
mas_makeConstraints只負(fù)責(zé)新增約束Autolayout不能同時(shí)存在兩條針對(duì)于同一對(duì)象的約束否則會(huì)報(bào)錯(cuò)
mas_updateConstraints針對(duì)上面的情況會(huì)更新在block中出現(xiàn)的約束不會(huì)導(dǎo)致出現(xiàn)兩個(gè)相同約束的情況
mas_remakeConstraints則會(huì)清除之前的所有約束僅保留最新的約束
三種函數(shù)善加利用就可以應(yīng)對(duì)各種情況了
*/
其次equalTo和mas_equalTo的區(qū)別在哪里呢?其實(shí)mas_equalTo是一個(gè)MACRO
#define mas_equalTo(...) ? ? ? ? ? ? ? ? equalTo(MASBoxValue((__VA_ARGS__)))
#define mas_greaterThanOrEqualTo(...) ? ?greaterThanOrEqualTo(MASBoxValue((__VA_ARGS__)))
#define mas_lessThanOrEqualTo(...) ? ? ? lessThanOrEqualTo(MASBoxValue((__VA_ARGS__)))
#define mas_offset(...) ? ? ? ? ? ? ? ? ?valueOffset(MASBoxValue((__VA_ARGS__)))
可以看到mas_equalTo只是對(duì)其參數(shù)進(jìn)行了一個(gè)BOX操作(裝箱) MASBoxValue的定義具體可以看看源代碼太長(zhǎng)就不貼出來(lái)了
所支持的類(lèi)型除了NSNumber支持的那些數(shù)值類(lèi)型之外就只支持CGPoint CGSize UIEdgeInsets
介紹完這幾個(gè)問(wèn)題我們就繼續(xù)往下了PS:剛才定義的sv會(huì)成為我們接下來(lái)所有sample的superView
1.1.2[初級(jí)]讓一個(gè)view略小于其superView(邊距為10)
UIView *sv1 = [UIViewnew];
[sv1 showPlaceHolder];
sv1.backgroundColor = [UIColor redColor];
[sv addSubview:sv1];
[sv1 mas_makeConstraints:^(MASConstraintMaker *make) {
make.edges.equalTo(sv).with.insets(UIEdgeInsetsMake(10, 10, 10, 10));
/*等價(jià)于
make.top.equalTo(sv).with.offset(10);
make.left.equalTo(sv).with.offset(10);
make.bottom.equalTo(sv).with.offset(-10);
make.right.equalTo(sv).with.offset(-10);
*/
/*也等價(jià)于
make.top.left.bottom.and.right.equalTo(sv).with.insets(UIEdgeInsetsMake(10, 10, 10, 10));
*/
}];
代碼效果
可以看到edges其實(shí)就是top,left,bottom,right的一個(gè)簡(jiǎn)化分開(kāi)寫(xiě)也可以一句話(huà)更省事
那么為什么bottom和right里的offset是負(fù)數(shù)呢?因?yàn)檫@里計(jì)算的是絕對(duì)的數(shù)值計(jì)算的bottom需要小魚(yú)sv的底部高度所以要-10同理用于right
這里有意思的地方是and和with其實(shí)這兩個(gè)函數(shù)什么事情都沒(méi)做
- (MASConstraint *)with{
returnself;
}
- (MASConstraint *)and {
returnself;
}
但是用在這種鏈?zhǔn)秸Z(yǔ)法中就非常的巧妙和易懂不得不佩服作者的心思(雖然我現(xiàn)在基本都會(huì)省略)
1.1.3[初級(jí)]讓兩個(gè)高度為150的view垂直居中且等寬且等間隔排列間隔為10(自動(dòng)計(jì)算其寬度)
int padding1 = 10;
[sv2 mas_makeConstraints:^(MASConstraintMaker *make) {
make.centerY.mas_equalTo(sv.mas_centerY);
make.left.equalTo(sv.mas_left).with.offset(padding1);
make.right.equalTo(sv3.mas_left).with.offset(-padding1);
make.height.mas_equalTo(@150);
make.width.equalTo(sv3);
}];
[sv3 mas_makeConstraints:^(MASConstraintMaker *make) {
make.centerY.mas_equalTo(sv.mas_centerY);
make.left.equalTo(sv2.mas_right).with.offset(padding1);
make.right.equalTo(sv.mas_right).with.offset(-padding1);
make.height.mas_equalTo(@150);
make.width.equalTo(sv2);
}];
代碼效果
這里我們?cè)趦蓚€(gè)子view之間互相設(shè)置的約束可以看到他們的寬度在約束下自動(dòng)的被計(jì)算出來(lái)了
1.1.4[中級(jí)]在UIScrollView順序排列一些view并自動(dòng)計(jì)算contentSize
UIScrollView *scrollView = [UIScrollViewnew];
scrollView.backgroundColor = [UIColor whiteColor];
[sv addSubview:scrollView];
[scrollView mas_makeConstraints:^(MASConstraintMaker *make) {
make.edges.equalTo(sv).with.insets(UIEdgeInsetsMake(5,5,5,5));
}];
UIView *container = [UIViewnew];
[scrollView addSubview:container];
[container mas_makeConstraints:^(MASConstraintMaker *make) {
make.edges.equalTo(scrollView);
make.width.equalTo(scrollView);
}];
int count = 10;
UIView *lastView = nil;
for( int i = 1 ; i <= count ; ++i )
{
UIView *subv = [UIViewnew];
[container addSubview:subv];
subv.backgroundColor = [UIColor colorWithHue:( arc4random() % 256 / 256.0 )
saturation:( arc4random() % 128 / 256.0 ) + 0.5
brightness:( arc4random() % 128 / 256.0 ) + 0.5
alpha:1];
[subv mas_makeConstraints:^(MASConstraintMaker *make) {
make.left.and.right.equalTo(container);
make.height.mas_equalTo(@(20*i));
if( lastView )
{
make.top.mas_equalTo(lastView.mas_bottom);
}
else
{
make.top.mas_equalTo(container.mas_top);
}
}];
lastView = subv;
}
[container mas_makeConstraints:^(MASConstraintMaker *make) {
make.bottom.equalTo(lastView.mas_bottom);
}];
頭部效果
尾部效果
從scrollView的scrollIndicator可以看出scrollView的內(nèi)部已如我們所想排列好了
這里的關(guān)鍵就在于container這個(gè)view起到了一個(gè)中間層的作用能夠自動(dòng)的計(jì)算uiscrollView的contentSize
1.1.5[高級(jí)]橫向或者縱向等間隙的排列一組view
很遺憾autoLayout并沒(méi)有直接提供等間隙排列的方法(Masonry的官方demo中也沒(méi)有對(duì)應(yīng)的案例)但是參考案例3我們可以通過(guò)一個(gè)小技巧來(lái)實(shí)現(xiàn)這個(gè)目的為此我寫(xiě)了一個(gè)Category
@implementation UIView(Masonry_LJC)
- (void) distributeSpacingHorizontallyWith:(NSArray*)views
{
NSMutableArray *spaces = [NSMutableArray arrayWithCapacity:views.count+1];
for( int i = 0 ; i < views.count+1 ; ++i )
{
UIView *v = [UIViewnew];
[spaces addObject:v];
[self addSubview:v];
[v mas_makeConstraints:^(MASConstraintMaker *make) {
make.width.equalTo(v.mas_height);
}];
}
UIView *v0 = spaces[0];
__weak __typeof(&*self)ws = self;
[v0 mas_makeConstraints:^(MASConstraintMaker *make) {
make.left.equalTo(ws.mas_left);
make.centerY.equalTo(((UIView*)views[0]).mas_centerY);
}];
UIView *lastSpace = v0;
for( int i = 0 ; i < views.count; ++i )
{
UIView *obj = views[i];
UIView *space = spaces[i+1];
[obj mas_makeConstraints:^(MASConstraintMaker *make) {
make.left.equalTo(lastSpace.mas_right);
}];
[space mas_makeConstraints:^(MASConstraintMaker *make) {
make.left.equalTo(obj.mas_right);
make.centerY.equalTo(obj.mas_centerY);
make.width.equalTo(v0);
}];
lastSpace = space;
}
[lastSpace mas_makeConstraints:^(MASConstraintMaker *make) {
make.right.equalTo(ws.mas_right);
}];
}
- (void) distributeSpacingVerticallyWith:(NSArray*)views
{
NSMutableArray *spaces = [NSMutableArray arrayWithCapacity:views.count+1];
for( int i = 0 ; i < views.count+1 ; ++i )
{
UIView *v = [UIViewnew];
[spaces addObject:v];
[self addSubview:v];
[v mas_makeConstraints:^(MASConstraintMaker *make) {
make.width.equalTo(v.mas_height);
}];
}
UIView *v0 = spaces[0];
__weak __typeof(&*self)ws = self;
[v0 mas_makeConstraints:^(MASConstraintMaker *make) {
make.top.equalTo(ws.mas_top);
make.centerX.equalTo(((UIView*)views[0]).mas_centerX);
}];
UIView *lastSpace = v0;
for( int i = 0 ; i < views.count; ++i )
{
UIView *obj = views[i];
UIView *space = spaces[i+1];
[obj mas_makeConstraints:^(MASConstraintMaker *make) {
make.top.equalTo(lastSpace.mas_bottom);
}];
[space mas_makeConstraints:^(MASConstraintMaker *make) {
make.top.equalTo(obj.mas_bottom);
make.centerX.equalTo(obj.mas_centerX);
make.height.equalTo(v0);
}];
lastSpace = space;
}
[lastSpace mas_makeConstraints:^(MASConstraintMaker *make) {
make.bottom.equalTo(ws.mas_bottom);
}];
}
@end
簡(jiǎn)單的來(lái)測(cè)試一下
UIView *sv11 = [UIViewnew];
UIView *sv12 = [UIViewnew];
UIView *sv13 = [UIViewnew];
UIView *sv21 = [UIViewnew];
UIView *sv31 = [UIViewnew];
sv11.backgroundColor = [UIColor redColor];
sv12.backgroundColor = [UIColor redColor];
sv13.backgroundColor = [UIColor redColor];
sv21.backgroundColor = [UIColor redColor];
sv31.backgroundColor = [UIColor redColor];
[sv addSubview:sv11];
[sv addSubview:sv12];
[sv addSubview:sv13];
[sv addSubview:sv21];
[sv addSubview:sv31];
//給予不同的大小測(cè)試效果
[sv11 mas_makeConstraints:^(MASConstraintMaker *make) {
make.centerY.equalTo(@[sv12,sv13]);
make.centerX.equalTo(@[sv21,sv31]);
make.size.mas_equalTo(CGSizeMake(40, 40));
}];
[sv12 mas_makeConstraints:^(MASConstraintMaker *make) {
make.size.mas_equalTo(CGSizeMake(70, 20));
}];
[sv13 mas_makeConstraints:^(MASConstraintMaker *make) {
make.size.mas_equalTo(CGSizeMake(50, 50));
}];
[sv21 mas_makeConstraints:^(MASConstraintMaker *make) {
make.size.mas_equalTo(CGSizeMake(50, 20));
}];
[sv31 mas_makeConstraints:^(MASConstraintMaker *make) {
make.size.mas_equalTo(CGSizeMake(40, 60));
}];
[sv distributeSpacingHorizontallyWith:@[sv11,sv12,sv13]];
[sv distributeSpacingVerticallyWith:@[sv11,sv21,sv31]];
[sv showPlaceHolderWithAllSubviews];
[sv hidePlaceHolder];
代碼效果
perfect!簡(jiǎn)潔明了的達(dá)到了我們所要的效果
1.2高級(jí)開(kāi)發(fā)技巧
1.2.1更新layout
1.2.1.1mas_updateConstraints
使用Masonry創(chuàng)建constraint來(lái)定義布局的方式有三種：mas_makeConstraints，mas_updateConstraints勒虾，mas_remakeConstraints。
有時(shí)你需要更新constraint(例如，動(dòng)畫(huà)和調(diào)試)而不是創(chuàng)建固定constraint掏导，可以使用mas_updateConstraints方法奠骄。
1.2.1.2mas_remakeConstraints
mas_remakeConstraints與mas_updateConstraints比較相似藕甩，都是更新constraint。不過(guò)锦爵，mas_remakeConstraints是刪除之前constraint，然后再添加新的constraint(適用于移動(dòng)動(dòng)畫(huà))奥裸；而mas_updateConstraints只是更新constraint的值险掀。
1.2.1.3代碼示例
[_loginButtonmas_remakeConstraints:^(MASConstraintMaker*make) {
make.width.equalTo(weakSelf.loginNameTextField.mas_width);
make.height.equalTo(weakSelf.loginNameTextField.mas_height);
make.centerX.mas_equalTo(weakSelf.loginContainerView.mas_centerX);
if(_loginVerifyImageCodeTextField) {
make.top.equalTo(weakSelf.loginVerifyImageCodeTextField.mas_bottom).with.offset(20);
}
}];
[_loginDescLabelmas_updateConstraints:^(MASConstraintMaker*make) {
make.top.equalTo(weakSelf.loginButton.mas_bottom).with.offset(5);
}];
1.3常見(jiàn)問(wèn)題
1.3.1在TableCell單元格中無(wú)法使用Masonry
在TableCell中增加子控件時(shí)，無(wú)法正常使用Masonry來(lái)進(jìn)行布局湾宙，可能是Cell重用引起的樟氢。
1.3.2使用了Masonry布局的控件最好手動(dòng)釋放內(nèi)存，若有APP自動(dòng)釋放內(nèi)存侠鳄，會(huì)有延遲埠啃，導(dǎo)致頁(yè)面布局失敗
//需要手動(dòng)釋放mas_makeConstraints的內(nèi)存，若有APP自動(dòng)釋放內(nèi)存伟恶，會(huì)有延遲碴开，導(dǎo)致頁(yè)面布局失敗
_loginNameTextField=nil;
_loginVerifyCodeGetButton=nil;
_loginVerifyCodeTextField=nil;
1.3.3盡量直接用equalTo，而不用mas_equalTo
mas_equalTo需要等控件自身布局完成了之后才能調(diào)用博秫，而equalTo不需要潦牛。因此進(jìn)行子視圖布局時(shí)，用前者容易掛機(jī)挡育。
1.3.4使用dispatch_get_main_queue保證布局與后續(xù)處理的同步
雖然mas_updateConstraints的block回調(diào)是順序執(zhí)行的巴碗，但是布局真正起作用還是放在了main_queue的下一個(gè)runloop中執(zhí)行的，所以如果要在布局完成后順序執(zhí)行某些處理（例如開(kāi)始進(jìn)行自定義繪制或者異步繪制）静盅，最好手動(dòng)放到main_queue的下一個(gè)runloop中執(zhí)行良价，確保布局完成后才開(kāi)始執(zhí)行代碼寝殴。
如下是示例代碼：
-(void)draw
{
[selfsetLayout];
//因?yàn)長(zhǎng)ayout庫(kù)是異步的，為了保證執(zhí)行順序上的同步明垢，需要作此處理
dispatch_async(dispatch_get_main_queue(), ^{
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT,0), ^{
CGRectdrawFrame =CGRectMake(0,0,SCREEN_BOUNDS.size.width,_headerHeight);
UIGraphicsBeginImageContextWithOptions(drawFrame.size,YES,0);
CGContextRefcontext =UIGraphicsGetCurrentContext();
if(!context) {
return;
}
[[UIColorwhiteColor]set];
CGContextFillRect(context,drawFrame);
[_separationLineViewdrawRect:CGRectMake(0,0,
drawFrame.size.width,_lineHeight)];
[_iconButtondrawRect:_iconButton.frame];
[_nameButtondrawRect:_nameButton.frame];
[_postDateLabeldrawRect:_postDateLabel.frame];
UIImage*tempImage =UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
dispatch_async(dispatch_get_main_queue(),^{
//_postContentTextImageView.frame= _postContentTextView.frame;//textViewRect;//
[_iconButtonsetHidden:NO];
[_nameButtonsetHidden:NO];
[_postDateLabelsetHidden:NO];
_bgImageView.image=nil;
_bgImageView.image=tempImage;
});
});
});
}
2參考鏈接
實(shí)時(shí)顯示iOS編寫(xiě)UI代碼效果
