iOS 分类：按顺序添加视图

一, 场景:

1. 在一个父视图上添加多个子视图的情况下, 有可能出现添加视图的时机有先后的问题, 后来的视图会遮盖住先来的视图.
2. 可以在添加子视图的时候, 获取需要展示的优先级大小..优先级越高, 就在已有视图更外层显示.

二, 分类方法代码如下:

// UIView+addsubview.h

@interface UIView (addsubview)
@property (nonatomic,assign) NSInteger sort;
- (void)addsubviewBysort:(UIView *)newView ;

@end

//UIView+addsubview.m

#import "UIView+addsubview.h"
#import <objc/runtime.h>
@implementation UIView (addsubview)
- (void)setSort:(NSInteger)sort{
    objc_setAssociatedObject(self, @selector(setSort:), @(sort), OBJC_ASSOCIATION_ASSIGN);
}

- (NSInteger)sort{
    NSNumber *num = objc_getAssociatedObject(self, @selector(setSort:));
    return num.integerValue;
}

- (void)addsubviewBysort:(UIView *)newView {
    BOOL bInsert = NO;
    for (NSInteger i = self.subviews.count - 1; i >= 0  ; i--) {
        UIView *subview = [self.subviews objectAtIndex:i];
        if (subview.sort <= newView.sort) {
            bInsert = YES;
            NSLog(@"lz--insert->%li---on:%li",(long)newView.sort,(long)subview.sort);
            [self insertSubview:newView aboveSubview:subview ];
            break;
        }
    }
    if (bInsert == NO) {
        NSLog(@"lz--below all->%li",(long)newView.sort);
        [self insertSubview:newView atIndex:0];
    }
}

- (NSInteger)getMaxSort{
    NSInteger maxSort = 0;
    for (UIView *subview in self.subviews) {
        if (maxSort < subview.sort) {
            maxSort = subview.sort;
        }
    }
    return maxSort;
}
@end

三, 调用方式代码如下:

- (void)test{
    for (int i = 100; i > 0; i--) {
        dispatch_async(dispatch_get_main_queue(), ^{
            UIView *view = [UIView new];
            view.sort = arc4random()%100;
            [self.view addsubviewBysort:view];
        });
    }
    
    
    dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(2 * NSEC_PER_SEC)), dispatch_get_main_queue(), ^{
        for (UIView *subview in self.view.subviews) {
            NSLog(@"lz-->%li",(long)subview.sort);
        }
    });

}