一、調用代碼使APP進入后臺，達到點擊Home鍵的效果。（私有API）
[[UIApplication sharedApplication] performSelector:@selector(suspend)];
suspend的英文意思：懸、掛、暫停
二、獲取UIWebView的高度 個人
(void)webViewDidFinishLoad:(UIWebView *)webView? {? ? ? CGFloat height = [[webView stringByEvaluatingJavaScriptFromString:@"document.body.offsetHeight"] floatValue];? ? ? CGRect frame = webView.frame;? ? ? webView.frame = CGRectMake(frame.origin.x, frame.origin.y, frame.size.width, height);? }
三、UITableView收起鍵盤何必這么麻煩 一個屬性搞定，效果好（UIScrollView同樣可以使用） 以前是不是覺得[self.view endEditing:YES];很屌，這個下面的更屌。 yourTableView.keyboardDismissMode = UIScrollViewKeyboardDismissModeOnDrag;
四、設置UILable ?的行間距 ?和 計算帶行間距的高度
/*
UILabel* 展示的控件
(NSString*)str? 內容
withFont:(float)font 字體大小
WithSpace:(float)space 行間距
*/
//給UILabel設置行間距和字間距
-(void)setLabelSpace:(UILabel*)label withValue:(NSString*)str withFont:(float)font WithSpace:(float)space{
NSMutableParagraphStyle *paraStyle = [[NSMutableParagraphStyle alloc] init];
paraStyle.lineBreakMode = NSLineBreakByCharWrapping;
paraStyle.alignment = NSTextAlignmentLeft;
paraStyle.lineSpacing = space; //設置行間距
paraStyle.hyphenationFactor = 1.0;
paraStyle.firstLineHeadIndent = 0.0;
paraStyle.paragraphSpacingBefore = 0.0;
paraStyle.headIndent = 0;
paraStyle.tailIndent = 0;
//設置字間距 NSKernAttributeName:@1.5f
UIFont *tfont = [UIFont systemFontOfSize:font];
NSDictionary *dic = @{NSFontAttributeName:tfont, NSParagraphStyleAttributeName:paraStyle, NSKernAttributeName:@1.5f
};
NSAttributedString *attributeStr = [[NSAttributedString alloc] initWithString:str attributes:dic];
label.attributedText = attributeStr;
}
/*
計算UILabel的高度(帶有行間距的情況)
(NSString*)str? 內容
withFont:(float)font 字體大小
WithSpace:(float)space 行間距
(CGFloat)width? UILable的寬度
*/
//計算UILabel的高度(帶有行間距的情況)
-(CGFloat)getSpaceLabelHeight:(NSString*)str withFont:(float)font withWidth:(CGFloat)width WithSpace:(float)space{
NSMutableParagraphStyle *paraStyle = [[NSMutableParagraphStyle alloc] init];
paraStyle.lineBreakMode = NSLineBreakByCharWrapping;
paraStyle.alignment = NSTextAlignmentLeft;
paraStyle.lineSpacing = space;
paraStyle.hyphenationFactor = 1.0;
paraStyle.firstLineHeadIndent = 0.0;
paraStyle.paragraphSpacingBefore = 0.0;
paraStyle.headIndent = 0;
paraStyle.tailIndent = 0;
UIFont *tfont = [UIFont systemFontOfSize:font];
NSDictionary *dic = @{NSFontAttributeName:tfont, NSParagraphStyleAttributeName:paraStyle, NSKernAttributeName:@1.5f
};
CGSize size = [str boundingRectWithSize:CGSizeMake(width, CGFLOAT_MAX) options:NSStringDrawingUsesLineFragmentOrigin attributes:dic context:nil].size;
return size.height;
}
五、 禁止程序運行時自動鎖屏 [[UIApplication sharedApplication] setIdleTimerDisabled:YES];
六、CocoaPods pod install/pod update更新慢的問題 pod install –verbose –no-repo-update pod update –verbose –no-repo-update 如果不加后面的參數，默認會升級CocoaPods的spec倉庫，加一個參數可以省略這一步，然后速度就會提升不少。
七、修改textFieldplaceholder字體顏色和大小
textField.placeholder = @"請輸入用戶名";? [textField setValue:[UIColor redColor] forKeyPath:@"_placeholderLabel.textColor"];? [textField setValue:[UIFont boldSystemFontOfSize:16] forKeyPath:@"_placeholderLabel.font"];
八、禁止textField和textView的復制粘貼菜單
-(BOOL)canPerformAction:(SEL)action withSender:(id)sender{? ? if ([UIMenuController sharedMenuController]) {? ? ? [UIMenuController sharedMenuController].menuVisible = NO;? ? }? ? return NO;}
九、級三級頁面隱藏系統tabbar 1、單個處理
YourViewController *yourVC = [YourViewController new];yourVC.hidesBottomBarWhenPushed = YES;[self.navigationController pushViewController:yourVC animated:YES];
十、取消系統的返回手勢
self.navigationController.interactivePopGestureRecognizer.enabled = NO;
十一、百度坐標跟火星坐標相互轉換
//百度轉火星坐標
+ (CLLocationCoordinate2D )bdToGGEncrypt:(CLLocationCoordinate2D)coord
{
double x = coord.longitude - 0.0065, y = coord.latitude - 0.006;
double z = sqrt(x * x + y * y) - 0.00002 * sin(y * M_PI);
double theta = atan2(y, x) - 0.000003 * cos(x * M_PI);
CLLocationCoordinate2D transformLocation ;
transformLocation.longitude = z * cos(theta);
transformLocation.latitude = z * sin(theta);
return transformLocation;
}
//火星坐標轉百度坐標
+ (CLLocationCoordinate2D )ggToBDEncrypt:(CLLocationCoordinate2D)coord
{
double x = coord.longitude, y = coord.latitude;
double z = sqrt(x * x + y * y) + 0.00002 * sin(y * M_PI);
double theta = atan2(y, x) + 0.000003 * cos(x * M_PI);
CLLocationCoordinate2D transformLocation ;
transformLocation.longitude = z * cos(theta) + 0.0065;
transformLocation.latitude = z * sin(theta) + 0.006;
return transformLocation;
}
十二、添加pch文件的步聚
1：創建新文件 ios->other->PCH file，創建一個pch文件：“工程名-Prefix.pch”：
2：將building setting中的precompile header選項的路徑添加“$(SRCROOT)/項目名稱/pch文件名”（例如：$(SRCROOT)/LotteryFive/LotteryFive-Prefix.pch）
3：將Precompile Prefix Header為YES，預編譯后的pch文件會被緩存起來，可以提高編譯速度
十三、關于Masonry
a:make.equalTo 或 make.greaterThanOrEqualTo （至多） 或 make.lessThanOrEqualTo（至少）
make.left.greaterThanOrEqualTo(label);
make.left.greaterThanOrEqualTo(label.mas_left);
//width >= 200 && width <= 400
make.width.greaterThanOrEqualTo(@200);
make.width.lessThanOrEqualTo(@400)
b：masequalTo 和 equalTo 區別：masequalTo 比equalTo多了類型轉換操作，一般來說，大多數時候兩個方法都是 通用的，但是對于數值元素使用mas_equalTo。對于對象或是多個屬性的處理，使用equalTo。特別是多個屬性時，必須使用equalTo
c：一些簡便賦值
// make top = superview.top + 5, left = superview.left + 10,
// bottom = superview.bottom - 15, right = superview.right - 20
make.edges.equalTo(superview).insets(UIEdgeInsetsMake(5, 10, 15, 20))
// make width and height greater than or equal to titleLabel
make.size.greaterThanOrEqualTo(titleLabel)
// make width = superview.width + 100, height = superview.height - 50
make.size.equalTo(superview).sizeOffset(CGSizeMake(100, -50))
// make centerX = superview.centerX - 5, centerY = superview.centerY + 10
make.center.equalTo(superview).centerOffset(CGPointMake(-5, 10))
d:and關鍵字運用
make.left.right.and.bottom.equalTo(superview);
make.top.equalTo(otherView);
e:優先；優先權(.priority,.priorityHigh,.priorityMedium,.priorityLow)
.priority允許您指定一個確切的優先級
.priorityHigh 等價于UILayoutPriorityDefaultHigh
.priorityMedium 介于高跟低之間
.priorityLow 等價于UILayoutPriorityDefaultLow
實例：
make.left.greaterThanOrEqualTo(label.mas_left).with.priorityLow();
make.top.equalTo(label.mas_top).with.priority(600);
g:使用mas_makeConstraints創建constraint后，你可以使用局部變量或屬性來保存以便下次引用它；如果創建多個constraints，你可以采用數組來保存它們
// 局部或者全局
@property (nonatomic, strong) MASConstraint *topConstraint;
// 創建約束并賦值
[view1 mas_makeConstraints:^(MASConstraintMaker *make) {
self.topConstraint = make.top.equalTo(superview.mas_top).with.offset(padding.top);
make.left.equalTo(superview.mas_left).with.offset(padding.left);
}];
// 過后可以直接訪問self.topConstraint
[self.topConstraint uninstall];
h:mas_updateConstraints更新約束，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
- (void)updateConstraints {
[self.growingButton mas_updateConstraints:^(MASConstraintMaker *make) {
make.center.equalTo(self);
make.width.equalTo(@(self.buttonSize.width)).priorityLow();
make.height.equalTo(@(self.buttonSize.height)).priorityLow();
make.width.lessThanOrEqualTo(self);
make.height.lessThanOrEqualTo(self);
}];
//調用父updateConstraints
[super updateConstraints];
}
i:mas_remakeConstraints更新約束，mas_remakeConstraints與mas_updateConstraints比較相似，都是更新constraint。不過，mas_remakeConstraints是刪除之前constraint，然后再添加新的constraint(適用于移動動畫)；而mas_updateConstraints只是更新constraint的值。
- (void)changeButtonPosition {
[self.button mas_remakeConstraints:^(MASConstraintMaker *make) {
make.size.equalTo(self.buttonSize);
if (topLeft) {
make.top.and.left.offset(10);
} else {
make.bottom.and.right.offset(-10);
}
}];
}
十四、UIWebView在IOS9下底部出現黑邊解決方式
UIWebView底部的黑條很難看(在IOS8下不會，在IOS9會出現)，特別是在底部還有透明控件的時候，隱藏的做法其實很簡單，只需要將opaque設為NO，背景色設為clearColor即可
十五、數組逆序遍歷
1、枚舉法
NSArray *array = @[@"1",@"2",@"3",@"5",@"6"];
[array enumerateObjectsWithOptions:NSEnumerationReverse usingBlock:^(id? _Nonnull obj, NSUInteger idx, BOOL * _Nonnull stop) {
NSLog(@"%@",obj);
}];
2、for循環
NSArray*array=@[@"1",@"2",@"3",@"5",@"6"];
for (NSInteger index = array.count-1; index>=0; index--) {
NSLog(@"%@",array[index]);
}
十六、把時間字符串2015-04-10格式化日期轉為NSDate類型
參考答案：
NSString *timeStr = @"2015-04-10";
NSDateFormatter *formatter = [[NSDateFormatter alloc] init];
formatter.dateFormat = @"yyyy-MM-dd";
formatter.timeZone = [NSTimeZone defaultTimeZone];
NSDate *date = [formatter dateFromString:timeStr];
// 2015-04-09 16:00:00 +0000
NSLog(@"%@", date);
十七 、簡單寫出增、刪、改、查的SQL語句。
參考答案：
數據庫的簡單操作，還是會的，大學可沒白學。
增：
insert into tb_blogs(name, url) values('aaa','http://www.baidu.com');
刪：
delete from tb_blogs where blogid = 1;
改：
update tb_blogs set url = 'www.baidu.com' where blogid = 1;
查：
select name, url from tb_blogs where blogid = 1;
