One

先總結下最近做專案遇到的一個小問題，建立UIView時，總是有一邊會出現一條灰黑線，原因竟是在給view設定frame時的精確度問題，取整下即可；

ceilf(width)

Two

#define demoScale  CGRectGetWidth([[UIScreen mainScreen] bounds])/375.0

- (void)forDemo{
    UIView *contentView = self.view;
    ///按鈕總個數
    NSInteger allCount = 16;
    ///按鈕每行總個數
    NSInteger elCount = 5
 
;
    ///左右邊距
    CGFloat marginLR = 25*demoScale;
    ///上下邊距
    CGFloat marginTD = 10*demoScale;
    ///button左右之間的間隔（item間距）
    CGFloat lineSpace = 30*demoScale;
    ///button上下之間的間隔（行間距）
    CGFloat columnSpace = 20*demoScale;
    ///button寬
    CGFloat btnWidth = (CGRectGetWidth(contentView.bounds) - marginLR*2
 
 - lineSpace*(elCount-1))/elCount;
    ///button高
    CGFloat btnHeight = 50*demoScale;

    for (int i = 0; i < allCount; i ++) {
        CGFloat btnX = marginLR + (i%elCount)*(btnWidth + lineSpace);
        CGFloat btnY = marginTD + (i/elCount)*(btnHeight + columnSpace);
        NSLog(@"%f,%f",btnX,btnY);
        UIButton 
 
*button = [UIButton buttonWithType:UIButtonTypeCustom];
        button.backgroundColor = [UIColor redColor];
        button.frame = CGRectMake(btnX , btnY, btnWidth, btnHeight);
        [contentView addSubview:button];
    }

    NSInteger columnNumber = (allCount/elCount);
    CGFloat contentViewHeiht = marginTD*2 + columnSpace*(columnNumber-1) +  columnNumber*btnHeight;
}