版本記錄
| 版本號 | 時間 |
|---|---|
| V1.0 | 2018.07.16 |
前言
我們做APP界面恶守，也就是布局UI第献，那么關于布局，我們有很多方法兔港，蘋果也都提供了支持庸毫，市場上我們用的并不是系統提供原生的layout，對于OC語言一般都是使用一個第三方的布局框架 —— Masonry衫樊。接下來幾篇我們就一起深入看一下這個框架飒赃。感興趣的看上面幾篇文章利花。
1. Masonry框架詳細解析（一） —— 基本概覽（一）
基本結構和API
首先我們看一下框架的基本結構。
接著载佳，一起看一下API接口
Masonry.h
#import <Foundation/Foundation.h>
//! Project version number for Masonry.
FOUNDATION_EXPORT double MasonryVersionNumber;
//! Project version string for Masonry.
FOUNDATION_EXPORT const unsigned char MasonryVersionString[];
#import "MASUtilities.h"
#import "View+MASAdditions.h"
#import "View+MASShorthandAdditions.h"
#import "ViewController+MASAdditions.h"
#import "NSArray+MASAdditions.h"
#import "NSArray+MASShorthandAdditions.h"
#import "MASConstraint.h"
#import "MASCompositeConstraint.h"
#import "MASViewAttribute.h"
#import "MASViewConstraint.h"
#import "MASConstraintMaker.h"
#import "MASLayoutConstraint.h"
#import "NSLayoutConstraint+MASDebugAdditions.h"
一起看一下這個API框架結構炒事。
約束入口
我們都是對視圖進行約束，所以入口就是一個UIView的分類蔫慧。
View+MASAdditions.h
大家對這個入口應該很熟悉吧
#import "MASUtilities.h"
#import "MASConstraintMaker.h"
#import "MASViewAttribute.h"
/**
* Provides constraint maker block
* and convience methods for creating MASViewAttribute which are view + NSLayoutAttribute pairs
*/
@interface MAS_VIEW (MASAdditions)
/**
* following properties return a new MASViewAttribute with current view and appropriate NSLayoutAttribute
*/
@property (nonatomic, strong, readonly) MASViewAttribute *mas_left;
@property (nonatomic, strong, readonly) MASViewAttribute *mas_top;
@property (nonatomic, strong, readonly) MASViewAttribute *mas_right;
@property (nonatomic, strong, readonly) MASViewAttribute *mas_bottom;
@property (nonatomic, strong, readonly) MASViewAttribute *mas_leading;
@property (nonatomic, strong, readonly) MASViewAttribute *mas_trailing;
@property (nonatomic, strong, readonly) MASViewAttribute *mas_width;
@property (nonatomic, strong, readonly) MASViewAttribute *mas_height;
@property (nonatomic, strong, readonly) MASViewAttribute *mas_centerX;
@property (nonatomic, strong, readonly) MASViewAttribute *mas_centerY;
@property (nonatomic, strong, readonly) MASViewAttribute *mas_baseline;
@property (nonatomic, strong, readonly) MASViewAttribute *(^mas_attribute)(NSLayoutAttribute attr);
#if (__IPHONE_OS_VERSION_MIN_REQUIRED >= 80000) || (__TV_OS_VERSION_MIN_REQUIRED >= 9000) || (__MAC_OS_X_VERSION_MIN_REQUIRED >= 101100)
@property (nonatomic, strong, readonly) MASViewAttribute *mas_firstBaseline;
@property (nonatomic, strong, readonly) MASViewAttribute *mas_lastBaseline;
#endif
#if (__IPHONE_OS_VERSION_MIN_REQUIRED >= 80000) || (__TV_OS_VERSION_MIN_REQUIRED >= 9000)
@property (nonatomic, strong, readonly) MASViewAttribute *mas_leftMargin;
@property (nonatomic, strong, readonly) MASViewAttribute *mas_rightMargin;
@property (nonatomic, strong, readonly) MASViewAttribute *mas_topMargin;
@property (nonatomic, strong, readonly) MASViewAttribute *mas_bottomMargin;
@property (nonatomic, strong, readonly) MASViewAttribute *mas_leadingMargin;
@property (nonatomic, strong, readonly) MASViewAttribute *mas_trailingMargin;
@property (nonatomic, strong, readonly) MASViewAttribute *mas_centerXWithinMargins;
@property (nonatomic, strong, readonly) MASViewAttribute *mas_centerYWithinMargins;
#endif
#if (__IPHONE_OS_VERSION_MAX_ALLOWED >= 110000) || (__TV_OS_VERSION_MAX_ALLOWED >= 110000)
@property (nonatomic, strong, readonly) MASViewAttribute *mas_safeAreaLayoutGuide API_AVAILABLE(ios(11.0),tvos(11.0));
@property (nonatomic, strong, readonly) MASViewAttribute *mas_safeAreaLayoutGuideTop API_AVAILABLE(ios(11.0),tvos(11.0));
@property (nonatomic, strong, readonly) MASViewAttribute *mas_safeAreaLayoutGuideBottom API_AVAILABLE(ios(11.0),tvos(11.0));
@property (nonatomic, strong, readonly) MASViewAttribute *mas_safeAreaLayoutGuideLeft API_AVAILABLE(ios(11.0),tvos(11.0));
@property (nonatomic, strong, readonly) MASViewAttribute *mas_safeAreaLayoutGuideRight API_AVAILABLE(ios(11.0),tvos(11.0));
#endif
/**
* a key to associate with this view
*/
@property (nonatomic, strong) id mas_key;
/**
* Finds the closest common superview between this view and another view
*
* @param view other view
*
* @return returns nil if common superview could not be found
*/
- (instancetype)mas_closestCommonSuperview:(MAS_VIEW *)view;
/**
* Creates a MASConstraintMaker with the callee view.
* Any constraints defined are added to the view or the appropriate superview once the block has finished executing
*
* @param block scope within which you can build up the constraints which you wish to apply to the view.
*
* @return Array of created MASConstraints
*/
- (NSArray *)mas_makeConstraints:(void(NS_NOESCAPE ^)(MASConstraintMaker *make))block;
/**
* Creates a MASConstraintMaker with the callee view.
* Any constraints defined are added to the view or the appropriate superview once the block has finished executing.
* If an existing constraint exists then it will be updated instead.
*
* @param block scope within which you can build up the constraints which you wish to apply to the view.
*
* @return Array of created/updated MASConstraints
*/
- (NSArray *)mas_updateConstraints:(void(NS_NOESCAPE ^)(MASConstraintMaker *make))block;
/**
* Creates a MASConstraintMaker with the callee view.
* Any constraints defined are added to the view or the appropriate superview once the block has finished executing.
* All constraints previously installed for the view will be removed.
*
* @param block scope within which you can build up the constraints which you wish to apply to the view.
*
* @return Array of created/updated MASConstraints
*/
- (NSArray *)mas_remakeConstraints:(void(NS_NOESCAPE ^)(MASConstraintMaker *make))block;
@end
這里有幾點需要說明：
1. 幾個屬性
首先我們看一下幾個屬性
/**
* following properties return a new MASViewAttribute with current view and appropriate NSLayoutAttribute
*/
@property (nonatomic, strong, readonly) MASViewAttribute *mas_left;
@property (nonatomic, strong, readonly) MASViewAttribute *mas_top;
@property (nonatomic, strong, readonly) MASViewAttribute *mas_right;
@property (nonatomic, strong, readonly) MASViewAttribute *mas_bottom;
@property (nonatomic, strong, readonly) MASViewAttribute *mas_leading;
@property (nonatomic, strong, readonly) MASViewAttribute *mas_trailing;
@property (nonatomic, strong, readonly) MASViewAttribute *mas_width;
@property (nonatomic, strong, readonly) MASViewAttribute *mas_height;
@property (nonatomic, strong, readonly) MASViewAttribute *mas_centerX;
@property (nonatomic, strong, readonly) MASViewAttribute *mas_centerY;
@property (nonatomic, strong, readonly) MASViewAttribute *mas_baseline;
@property (nonatomic, strong, readonly) MASViewAttribute *(^mas_attribute)(NSLayoutAttribute attr);
這里挠乳，這些屬性返回一個當前view的一個新的MASViewAttribute以及合適的NSLayoutAttribute。
我們先看一下這個返回的MASViewAttribute對象
/**
* An immutable tuple which stores the view and the related NSLayoutAttribute.
* Describes part of either the left or right hand side of a constraint equation
*/
@interface MASViewAttribute : NSObject
這個對象是一個存儲視圖和相關NSLayoutAttribute的不可變元組姑躲。描述約束方程左側或右側的一部分睡扬。
2. 宏判斷
接著就是幾個宏判斷。
#if (__IPHONE_OS_VERSION_MIN_REQUIRED >= 80000) || (__TV_OS_VERSION_MIN_REQUIRED >= 9000) || (__MAC_OS_X_VERSION_MIN_REQUIRED >= 101100)
@property (nonatomic, strong, readonly) MASViewAttribute *mas_firstBaseline;
@property (nonatomic, strong, readonly) MASViewAttribute *mas_lastBaseline;
#endif
#if (__IPHONE_OS_VERSION_MIN_REQUIRED >= 80000) || (__TV_OS_VERSION_MIN_REQUIRED >= 9000)
@property (nonatomic, strong, readonly) MASViewAttribute *mas_leftMargin;
@property (nonatomic, strong, readonly) MASViewAttribute *mas_rightMargin;
@property (nonatomic, strong, readonly) MASViewAttribute *mas_topMargin;
@property (nonatomic, strong, readonly) MASViewAttribute *mas_bottomMargin;
@property (nonatomic, strong, readonly) MASViewAttribute *mas_leadingMargin;
@property (nonatomic, strong, readonly) MASViewAttribute *mas_trailingMargin;
@property (nonatomic, strong, readonly) MASViewAttribute *mas_centerXWithinMargins;
@property (nonatomic, strong, readonly) MASViewAttribute *mas_centerYWithinMargins;
#endif
#if (__IPHONE_OS_VERSION_MAX_ALLOWED >= 110000) || (__TV_OS_VERSION_MAX_ALLOWED >= 110000)
@property (nonatomic, strong, readonly) MASViewAttribute *mas_safeAreaLayoutGuide API_AVAILABLE(ios(11.0),tvos(11.0));
@property (nonatomic, strong, readonly) MASViewAttribute *mas_safeAreaLayoutGuideTop API_AVAILABLE(ios(11.0),tvos(11.0));
@property (nonatomic, strong, readonly) MASViewAttribute *mas_safeAreaLayoutGuideBottom API_AVAILABLE(ios(11.0),tvos(11.0));
@property (nonatomic, strong, readonly) MASViewAttribute *mas_safeAreaLayoutGuideLeft API_AVAILABLE(ios(11.0),tvos(11.0));
@property (nonatomic, strong, readonly) MASViewAttribute *mas_safeAreaLayoutGuideRight API_AVAILABLE(ios(11.0),tvos(11.0));
#endif
可能有人會問黍析，這塊是做什么的卖怜，其實就是根據不同系統定義的不同屬性，比如說11系統出來的safeAreaLayoutGuide阐枣，這個就只有在11系統中使用马靠，所以才需要進行版本判斷。
// 表示系統大于8.0
__IPHONE_OS_VERSION_MIN_REQUIRED >= 80000
// 當前SDK的最高版本, 在手機上, 就是該手機上支持的SDK最高版本侮繁，這里表示最大的支持的版本是11.0
__IPHONE_OS_VERSION_MAX_ALLOWED >= 110000
3. 幾個重要入口方法
下面這幾個方法大家都用過虑粥，也是Masonry應用的基本入口，下面我們就分著看一下宪哩。
1）尋找兩個視圖的最近的父視圖
/**
* Finds the closest common superview between this view and another view
*
* @param view other view
*
* @return returns nil if common superview could not be found
*/
- (instancetype)mas_closestCommonSuperview:(MAS_VIEW *)view;
該方法的作用就是尋找本視圖和另外一個視圖最近的父視圖娩贷。這個我們用的其實比較少，大家熟悉理解下就好锁孟。
2）make構建約束
我們一般使用下面這個方法構建約束彬祖。
/**
* Creates a MASConstraintMaker with the callee view.
* Any constraints defined are added to the view or the appropriate superview once the block has finished executing
*
* @param block scope within which you can build up the constraints which you wish to apply to the view.
*
* @return Array of created MASConstraints
*/
- (NSArray *)mas_makeConstraints:(void(NS_NOESCAPE ^)(MASConstraintMaker *make))block;
這個方法大家基本都用過，也是最熟悉的品抽，就是用來進行約束的储笑。該方法根據傳入的view創(chuàng)建一個MASConstraintMaker，一旦block結束執(zhí)行圆恤，任何定義的約束都被添加到view或者合適的superview上突倍。返回值就是一個創(chuàng)建的MASConstraints數組。
3）update約束
/**
* Creates a MASConstraintMaker with the callee view.
* Any constraints defined are added to the view or the appropriate superview once the block has finished executing.
* If an existing constraint exists then it will be updated instead.
*
* @param block scope within which you can build up the constraints which you wish to apply to the view.
*
* @return Array of created/updated MASConstraints
*/
- (NSArray *)mas_updateConstraints:(void(NS_NOESCAPE ^)(MASConstraintMaker *make))block;
該方法根據傳入的view創(chuàng)建一個MASConstraintMaker盆昙，一旦block結束執(zhí)行羽历，任何定義的約束都被添加到view或者合適的superview上。如果一個約束存在淡喜，那么它會替代到本次更新的約束秕磷。返回值是一個創(chuàng)建的/更新的約束的數組。
4）remake約束
/**
* Creates a MASConstraintMaker with the callee view.
* Any constraints defined are added to the view or the appropriate superview once the block has finished executing.
* All constraints previously installed for the view will be removed.
*
* @param block scope within which you can build up the constraints which you wish to apply to the view.
*
* @return Array of created/updated MASConstraints
*/
- (NSArray *)mas_remakeConstraints:(void(NS_NOESCAPE ^)(MASConstraintMaker *make))block;
該方法用于根據傳入的view創(chuàng)建一個MASConstraintMaker炼团，一旦block結束執(zhí)行澎嚣，任何定義的約束都被添加到view或者合適的superview上疏尿。該view的所有以前的約束都將被remove掉，返回值是一個創(chuàng)建的/更新的約束的數組易桃。該方法與update的區(qū)別是褥琐，update是更新相同的約束，而remake是完全刪除以前的約束晤郑，使用本次重新創(chuàng)建的約束踩衩。
你為什么可以make很多個布局屬性
其實這個是一個響應式編程的問題，我們在使用的時候一般都是下面這種類似的使用方式贩汉。
make.height.width.equalTo(@(100));
這里的make其實是block的回調，帶的類型的參數MASConstraintMaker锚赤，MASConstraintMaker從名字上大家都可以猜測的差不多匹舞，這個其實就是進行約束的工廠方法。
@property (nonatomic, strong, readonly) MASConstraint *width;
@property (nonatomic, strong, readonly) MASConstraint *height;
... ...
當我們調用make.height的時候其實就是實現了下面這個方法
- (MASConstraint *)height {
return [self addConstraintWithLayoutAttribute:NSLayoutAttributeHeight];
}
該getter方法返回的是一個MASConstraint對象线脚，
然后調用.width方法赐稽，就會調用MASConstraint對象中width的getter方法。
/**
* Creates a new MASCompositeConstraint with the called attribute and reciever
*/
- (MASConstraint *)width;
getter方法實現如下所示：
- (MASConstraint *)width {
return [self addConstraintWithLayoutAttribute:NSLayoutAttributeWidth];
}
大家可以看見返回的仍然是MASConstraint浑侥，所以你就一直可以點語法進行約束姊舵。
關于這個以后會分篇幅進行詳細的說明，這里只是簡單的提一下寓落。
參考文章
1. __IPHONE_OS_VERSION_MIN_REQUIRED 和 __IPHONE_OS_VERSION_MAX_ALLOWED
2. iOS開發(fā)之Masonry框架源碼解析
后記
本篇主要講述了基本結構API和約束入口括丁，感興趣的給個贊或者關注~~~~
