這裏主要講一些我在日常開發中用到的一些小的技巧，其實也算不上技巧吧，就是省去一些不必要的代碼，或者有的小問題困擾你很久說不行在這裏你能找到答案
在UIView的擴展 快速修改frame
在iOS修改view的frame，我們經常需要寫一大堆代碼，來修改frame中的一個小屬性，這裏有一個方法，就是直接修改frame的每個值
新建一個category UIView+PPSFrame.h
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#import <UIKit/UIKit.h> @interface UIView (PPSFrame) @property (assign, nonatomic) CGFloat top;//上 相當於frame.origin.y @property (assign, nonatomic) CGFloat bottom;//下 相當於frame.size.height + frame.origin.y @property (assign, nonatomic) CGFloat left;//相當於frame.origin.x @property (assign, nonatomic) CGFloat right;//相當於frame.origin.x+frame.size.width @property (assign, nonatomic) CGFloat centerX; @property (assign, nonatomic) CGFloat centerY; @property (assign, nonatomic) CGFloat width; @property (assign, nonatomic) CGFloat height; @property (assign, nonatomic) CGSize size; @end
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在.m文件中設置各個屬性
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#import "UIView+Layout.h" @implementation UIView (Layout) @dynamic top; @dynamic bottom; @dynamic left; @dynamic right; @dynamic width; @dynamic height; @dynamic size; - (CGFloat)top { return self.frame.origin.y; } - (void)setTop:(CGFloat)top { CGRect frame = self.frame; frame.origin.y = top; self.frame = frame; } - (CGFloat)left { return self.frame.origin.x; } - (void)setLeft:(CGFloat)left { CGRect frame = self.frame; frame.origin.x = left; self.frame = frame; } - (CGFloat)bottom { return self.frame.size.height + self.frame.origin.y; } - (void)setBottom:(CGFloat)bottom { CGRect frame = self.frame; frame.origin.y = bottom - frame.size.height; self.frame = frame; } - (CGFloat)right { return self.frame.size.width + self.frame.origin.x; } - (void)setRight:(CGFloat)right { CGRect frame = self.frame; frame.origin.x = right - frame.size.width; self.frame = frame; } - (CGFloat)centerX { return self.center.x; } - (void)setCenterX:(CGFloat)centerX { CGPoint center = self.center; center.x = centerX; self.center = center; } - (CGFloat)centerY { return self.center.y; } - (void)setCenterY:(CGFloat)centerY { CGPoint center = self.center; center.y = centerY; self.center = center; } - (CGFloat)width { return self.frame.size.width; } - (void)setWidth:(CGFloat)width { CGRect frame = self.frame; frame.size.width = width; self.frame = frame; } - (CGFloat)height { return self.frame.size.height; } - (void)setHeight:(CGFloat)height { CGRect frame = self.frame; frame.size.height = height; self.frame = frame; } - (CGSize)size { return self.frame.size; } - (void)setSize:(CGSize)size { CGRect frame = self.frame; frame.size = size; self.frame = frame; } @end
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iOS OC項目的pch文件使用
在項目中如果我們需要一些公共的引用，或者一些全局的宏 那我們經常在pch中設置好
具體怎麼設置呢 在項目下新建一個pch文件
一般我會取名 項目名-PrefixHeader
在target——>Bulid Setting 中 設置 PrefixHeader
我的項目文件夾結構
$(SRCROOT)這個是指工程的根目錄
找到這個pch文件就行 然後啓動APP就會編譯這個文件了
pch.h中
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// // APP-1-PrefixHeader.pch // APP-1 // // Created by 羊謙 on 2016/10/28. // Copyright © 2016年 羊謙. All rights reserved. // #ifndef APP_1_PrefixHeader_pch #define APP_1_PrefixHeader_pch //在這裏直接定義你的宏變量 或者公共引用就行 #endif /* APP_1_PrefixHeader_pch */
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UITableView的Group樣式下頂部空白處理
要給tableHeaderView賦一個高度不爲0的view才能處理頂部留白
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//分組列表頭部空白處理 UIView *view = [[UIView alloc] initWithFrame:CGRectMake(0, 0, 0, 0.1)]; self.tableView.tableHeaderView = view;
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獲取某個view的Controller
其實就是根據view的響應鏈，來查找viewcontroller
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- (UIViewController *)viewController { UIViewController *viewController = nil; UIResponder *next = self.nextResponder; while (next) { if ([next isKindOfClass:[UIViewController class]]) { viewController = (UIViewController *)next; break; } next = next.nextResponder; } return viewController; }
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清空NSUserDefaults的記錄
方法一：是獲取當前的app的bundleId NSUserDefaults中有方法根據bundleId清空記錄
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NSString *appDomain = [[NSBundle mainBundle] bundleIdentifier]; [[NSUserDefaults standardUserDefaults] removePersistentDomainForName:appDomain];
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方法二：獲取所有存儲在NSUserDefaults中的數據，因爲是按照key-value形式存儲，所以循環key就能夠刪除數據
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- (void)clearDefaults{ NSUserDefaults * defs = [NSUserDefaults standardUserDefaults]; NSDictionary * dict = [defs dictionaryRepresentation]; for (id key in dict) { [defs removeObjectForKey:key]; } [defs synchronize]; }
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GCD timer定時器的使用
這裏的定時器，是一個每秒在主線程跑的一個方法
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__block int countSecond = 30; //倒計時 dispatch_queue_t queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0); dispatch_source_t timer = dispatch_source_create(DISPATCH_SOURCE_TYPE_TIMER, 0, 0,queue); dispatch_source_set_timer(timer,dispatch_walltime(NULL, 0),1.0*NSEC_PER_SEC, 0); //每秒執行 dispatch_source_set_event_handler(timer, ^{ if (countSecond==0) { //倒計時完畢 //@"倒計時結束，關閉" dispatch_source_cancel(timer); dispatch_async(dispatch_get_main_queue(), ^{ //倒計時完畢需要執行的操作 }); }else{ //倒計時 NSLog(@"%@", [NSString stringWithFormat:@"%ld",(long)countSecond]); dispatch_async(dispatch_get_main_queue(), ^{ //每秒需要執行的操作 //在這裏更新UI之類的 }); countSecond--; } }); dispatch_resume(timer);
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計算文件大小
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- (long long)fileSizeAtPath:(NSString *)path { NSFileManager *fileManager = [NSFileManager defaultManager]; if ([fileManager fileExistsAtPath:path]) { long long size = [fileManager attributesOfItemAtPath:path error:nil].fileSize; return size; } return 0; }
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計算文件夾大小
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- (long long)folderSizeAtPath:(NSString *)path { NSFileManager *fileManager = [NSFileManager defaultManager]; long long folderSize = 0; if ([fileManager fileExistsAtPath:path]) { NSArray *childerFiles = [fileManager subpathsAtPath:path]; for (NSString *fileName in childerFiles) { NSString *fileAbsolutePath = [path stringByAppendingPathComponent:fileName]; if ([fileManager fileExistsAtPath:fileAbsolutePath]) { long long size = [fileManager attributesOfItemAtPath:fileAbsolutePath error:nil].fileSize; folderSize += size; } } } return folderSize; }
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向上取整和向下取整
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floor(x)函數，是一個向下取整函數，是一個C函數 即是去不大於x的一個最大整數 floor(3.12) = 3 floor(4.9) = 4 與floor(x)函數對應的是ceil函數 這個即是向上取整了 ceil(3.9) = 4 ceil(1.2) = 2
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給任何一個view設置一張圖片
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UIImage *image = [UIImage imageNamed:@"image"]; self.MYView.layer.contents = (__bridge id _Nullable)(image.CGImage); self.MYView.layer.contentsRect = CGRectMake(0, 0, 0.5, 0.5);
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