Masonry手寫Autolayout專題
Masonry常規開發指導整理自此篇文檔（可別說我轉載不註明出處哦，^_^），後面加入了筆者在實際開發使用過程中遇到過的一些問題，希望對你有所幫助。
Masonry介紹與使用實踐：快速上手Autolayout
http://www.cocoachina.com/ios/20141219/10702.html
1 Masonry開發技巧
1.1 簡單使用技巧
1.1.1 [基礎] 居中顯示一個view
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- (void)viewDidLoad { [super viewDidLoad]; // Do any additional setup after loading the view.
WS(ws);
UIView *sv = [UIView new]; [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
使用我之間寫的MMPlaceHolder可以看到superview已經按照我們預期居中並且設置成了適當的大小
那麼先看看這幾行代碼
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//從此以後基本可以拋棄CGRectMake了 UIView *sv = [UIView new]; //在做autoLayout之前 一定要先將view添加到superview上 否則會報錯 [self.view addSubview:sv]; //mas_makeConstraints就是Masonry的autolayout添加函數 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設置成(300,300) make.size.mas_equalTo(CGSizeMake(300, 300)); }]; |
這裏有兩個問題要分解一下
首先在Masonry中能夠添加autolayout約束有三個函數
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- (NSArray *)mas_makeConstraints:(void(^)(MASConstraintMaker *make))block; - (NSArray *)mas_updateConstraints:(void(^)(MASConstraintMaker *make))block; - (NSArray *)mas_remakeConstraints:(void(^)(MASConstraintMaker *make))block; /* mas_makeConstraints 只負責新增約束 Autolayout不能同時存在兩條針對於同一對象的約束 否則會報錯 mas_updateConstraints 針對上面的情況 會更新在block中出現的約束 不會導致出現兩個相同約束的情況 mas_remakeConstraints 則會清除之前的所有約束 僅保留最新的約束 三種函數善加利用 就可以應對各種情況了 */ |
其次 equalTo和 mas_equalTo的區別在哪裏呢?其實 mas_equalTo是一個MACRO
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#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只是對其參數進行了一個BOX操作(裝箱) MASBoxValue的定義具體可以看看源代碼太長就不貼出來了
所支持的類型除了NSNumber支持的那些數值類型之外就只支持CGPoint CGSize UIEdgeInsets
介紹完這幾個問題我們就繼續往下了 PS:剛纔定義的sv會成爲我們接下來所有sample的superView
1.1.2 [初級] 讓一個view略小於其superView(邊距爲10)
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UIView *sv1 = [UIView new]; [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));
/* 等價於 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); */
/* 也等價於 make.top.left.bottom.and.right.equalTo(sv).with.insets(UIEdgeInsetsMake(10, 10, 10, 10)); */ }]; |
代碼效果
可以看到 edges其實就是top,left,bottom,right的一個簡化，分開寫也可以一句話更省事
那麼爲什麼bottom和right裏的offset是負數呢?因爲這裏計算的是絕對的數值計算的bottom需要小魚sv的底部高度所以要-10同理用於right
這裏有意思的地方是and和with其實這兩個函數什麼事情都沒做
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- (MASConstraint *)with { return self; } - (MASConstraint *)and { return self; } |
但是用在這種鏈式語法中就非常的巧妙和易懂不得不佩服作者的心思(雖然我現在基本都會省略)
1.1.3 [初級] 讓兩個高度爲150的view垂直居中且等寬且等間隔排列 間隔爲10(自動計算其寬度)
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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
這裏我們在兩個子view之間互相設置的約束可以看到他們的寬度在約束下自動的被計算出來了
1.1.4 [中級] 在UIScrollView順序排列一些view並自動計算contentSize
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UIScrollView *scrollView = [UIScrollView new]; 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 = [UIView new]; [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 = [UIView new]; [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的內部已如我們所想排列好了。這裏的關鍵就在於container這個view起到了一箇中間層的作用能夠自動的計算uiscrollView的contentSize。
1.1.5 [高級] 橫向或者縱向等間隙的排列一組view
很遺憾 autoLayout並沒有直接提供等間隙排列的方法(Masonry的官方demo中也沒有對應的案例)但是參考案例3我們可以通過一個小技巧來實現這個目的爲此我寫了一個Category
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@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 = [UIView new]; [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 = [UIView new]; [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 |
簡單的來測試一下
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UIView *sv11 = [UIView new]; UIView *sv12 = [UIView new]; UIView *sv13 = [UIView new]; UIView *sv21 = [UIView new]; UIView *sv31 = [UIView new]; 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!簡潔明瞭的達到了我們所要的效果
1.2 高級開發技巧
1.2.1 更新layout
1.2.1.1 mas_updateConstraints
使用Masonry創建constraint來定義佈局的方式有三種：mas_makeConstraints， mas_updateConstraints，mas_remakeConstraints。
有時你需要更新constraint(例如，動畫和調試)而不是創建固定constraint，可以使用mas_updateConstraints方法。
1.2.1.2 mas_remakeConstraints
mas_remakeConstraints與mas_updateConstraints比較相似，都是更新constraint。不過，mas_remakeConstraints是刪除之前constraint，然後再添加新的constraint(適用於移動動畫)；而mas_updateConstraints只是更新constraint的值。
1.2.1.3 代碼示例
[_loginButton mas_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);
}
}];
[_loginDescLabel mas_updateConstraints:^(MASConstraintMaker *make) {
make.top.equalTo(weakSelf.loginButton.mas_bottom).with.offset(5);
}];
1.3 常見問題
1.3.1 在TableCell單元格中無法使用Masonry
在TableCell中增加子控件時，無法正常使用Masonry來進行佈局，可能是Cell重用引起的。
1.3.2 使用了Masonry佈局的控件最好手動釋放內存，若有APP自動釋放內存，會有延遲，導致頁面佈局失敗
//需要手動釋放mas_makeConstraints的內存，若有APP自動釋放內存，會有延遲，導致頁面佈局失敗
_loginNameTextField = nil;
_loginVerifyCodeGetButton =nil;
_loginVerifyCodeTextField = nil;
1.3.3 儘量直接用equalTo，而不用mas_equalTo
mas_equalTo需要等控件自身佈局完成了之後才能調用，而equalTo不需要。因此進行子視圖佈局時，用前者容易掛機。
1.3.4 使用dispatch_get_main_queue保證佈局與後續處理的同步
雖然mas_updateConstraints的block回調是順序執行的，但是佈局真正起作用還是放在了main_queue的下一個runloop中執行的，所以如果要在佈局完成後順序執行某些處理（例如開始進行自定義繪製或者異步繪製），最好手動放到main_queue的下一個runloop中執行，確保佈局完成後纔開始執行代碼。
如下是示例代碼：
-(void)draw
{
[selfsetLayout];
//因爲Layout庫是異步的，爲了保證執行順序上的同步，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;
}
[[UIColor whiteColor] set];
CGContextFillRect(context,drawFrame);
[_separationLineViewdrawRect:CGRectMake(0,0,drawFrame.size.width,_lineHeight)];
[_iconButton drawRect:_iconButton.frame];
[_nameButton drawRect:_nameButton.frame];
[_postDateLabel drawRect:_postDateLabel.frame];
UIImage*tempImage =UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
dispatch_async(dispatch_get_main_queue(),^{
// _postContentTextImageView.frame= _postContentTextView.frame;//textViewRect;//
[_iconButton setHidden:NO];
[_nameButton setHidden:NO];
[_postDateLabelsetHidden:NO];
_bgImageView.image =nil;
_bgImageView.image =tempImage;
});
});
});
}
2 參考鏈接
實時顯示iOS編寫UI代碼效果
http://blog.csdn.net/zhang_red/article/details/45503683
Masonry介紹與使用實踐：快速上手Autolayout
http://www.cocoachina.com/ios/20141219/10702.html